gp8psk: Fix DVB frontend attach

The DVB binding schema at the DVB core assumes that the frontend is a
separate driver.  Faling to do that causes OOPS when the module is
removed, as it tries to do a symbol_put_addr on an internal symbol,
causing craches like:

    WARNING: CPU: 1 PID: 28102 at kernel/module.c:1108 module_put+0x57/0x70
    Modules linked in: dvb_usb_gp8psk(-) dvb_usb dvb_core nvidia_drm(PO) nvidia_modeset(PO) snd_hda_codec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd soundcore nvidia(PO) [last unloaded: rc_core]
    CPU: 1 PID: 28102 Comm: rmmod Tainted: P        WC O 4.8.4-build.1 #1
    Hardware name: MSI MS-7309/MS-7309, BIOS V1.12 02/23/2009
    Call Trace:
       dump_stack+0x44/0x64
       __warn+0xfa/0x120
       module_put+0x57/0x70
       module_put+0x57/0x70
       warn_slowpath_null+0x23/0x30
       module_put+0x57/0x70
       gp8psk_fe_set_frontend+0x460/0x460 [dvb_usb_gp8psk]
       symbol_put_addr+0x27/0x50
       dvb_usb_adapter_frontend_exit+0x3a/0x70 [dvb_usb]

From Derek's tests:
    "Attach bug is fixed, tuning works, module unloads without
     crashing. Everything seems ok!"

Reported-by: Derek <user.vdr@gmail.com>
Tested-by: Derek <user.vdr@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/media/dvb-frontends/gp8psk-fe.h

@@ -0,0 +1,82 @@
+/*
+ * gp8psk_fe driver
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef GP8PSK_FE_H
+#define GP8PSK_FE_H
+
+#include <linux/types.h>
+
+/* gp8psk commands */
+
+#define GET_8PSK_CONFIG                 0x80    /* in */
+#define SET_8PSK_CONFIG                 0x81
+#define I2C_WRITE			0x83
+#define I2C_READ			0x84
+#define ARM_TRANSFER                    0x85
+#define TUNE_8PSK                       0x86
+#define GET_SIGNAL_STRENGTH             0x87    /* in */
+#define LOAD_BCM4500                    0x88
+#define BOOT_8PSK                       0x89    /* in */
+#define START_INTERSIL                  0x8A    /* in */
+#define SET_LNB_VOLTAGE                 0x8B
+#define SET_22KHZ_TONE                  0x8C
+#define SEND_DISEQC_COMMAND             0x8D
+#define SET_DVB_MODE                    0x8E
+#define SET_DN_SWITCH                   0x8F
+#define GET_SIGNAL_LOCK                 0x90    /* in */
+#define GET_FW_VERS			0x92
+#define GET_SERIAL_NUMBER               0x93    /* in */
+#define USE_EXTRA_VOLT                  0x94
+#define GET_FPGA_VERS			0x95
+#define CW3K_INIT			0x9d
+
+/* PSK_configuration bits */
+#define bm8pskStarted                   0x01
+#define bm8pskFW_Loaded                 0x02
+#define bmIntersilOn                    0x04
+#define bmDVBmode                       0x08
+#define bm22kHz                         0x10
+#define bmSEL18V                        0x20
+#define bmDCtuned                       0x40
+#define bmArmed                         0x80
+
+/* Satellite modulation modes */
+#define ADV_MOD_DVB_QPSK 0     /* DVB-S QPSK */
+#define ADV_MOD_TURBO_QPSK 1   /* Turbo QPSK */
+#define ADV_MOD_TURBO_8PSK 2   /* Turbo 8PSK (also used for Trellis 8PSK) */
+#define ADV_MOD_TURBO_16QAM 3  /* Turbo 16QAM (also used for Trellis 8PSK) */
+
+#define ADV_MOD_DCII_C_QPSK 4  /* Digicipher II Combo */
+#define ADV_MOD_DCII_I_QPSK 5  /* Digicipher II I-stream */
+#define ADV_MOD_DCII_Q_QPSK 6  /* Digicipher II Q-stream */
+#define ADV_MOD_DCII_C_OQPSK 7 /* Digicipher II offset QPSK */
+#define ADV_MOD_DSS_QPSK 8     /* DSS (DIRECTV) QPSK */
+#define ADV_MOD_DVB_BPSK 9     /* DVB-S BPSK */
+
+/* firmware revision id's */
+#define GP8PSK_FW_REV1			0x020604
+#define GP8PSK_FW_REV2			0x020704
+#define GP8PSK_FW_VERS(_fw_vers) \
+	((_fw_vers)[2]<<0x10 | (_fw_vers)[1]<<0x08 | (_fw_vers)[0])
+
+struct gp8psk_fe_ops {
+	int (*in)(void *priv, u8 req, u16 value, u16 index, u8 *b, int blen);
+	int (*out)(void *priv, u8 req, u16 value, u16 index, u8 *b, int blen);
+	int (*reload)(void *priv);
+};
+
+struct dvb_frontend *gp8psk_fe_attach(const struct gp8psk_fe_ops *ops,
+				      void *priv, bool is_rev1);
+
+#endif