ASoC: rockchip: i2s: configure the sdio pins' iomux mode

There are 3 i2s sdio pins, which iomux mode is as follows:

 - sdi3_sdo1
 - sdi2_sdo2
 - sdi1_sdo3

we need to configure these pins' iomux mode via the GRF register
when use multi channel playback/capture.

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/rockchip/rockchip_i2s.h

@@ -236,4 +236,11 @@ enum {
 #define I2S_TXDR	(0x0024)
 #define I2S_RXDR	(0x0028)
 
+/* io direction cfg register */
+#define I2S_IO_DIRECTION_MASK	(7)
+#define I2S_IO_8CH_OUT_2CH_IN	(0)
+#define I2S_IO_6CH_OUT_4CH_IN	(4)
+#define I2S_IO_4CH_OUT_6CH_IN	(6)
+#define I2S_IO_2CH_OUT_8CH_IN	(7)
+
 #endif /* _ROCKCHIP_IIS_H */