s390/css: introduce cio_register_early_subchannels

Use cio_register_early_subchannels to register early subchannels
which are already in use. Call this function before we do the
actual subchannel scanning loop. This helps us to get rid of some
more special cases regarding the console subchannel.

Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/cio.h

@@ -129,11 +129,11 @@ void do_IRQ(struct pt_regs *);
 #ifdef CONFIG_CCW_CONSOLE
 extern struct subchannel *cio_probe_console(void);
 extern int cio_is_console(struct subchannel_id);
-extern struct subchannel *cio_get_console_subchannel(void);
+extern void cio_register_early_subchannels(void);
 extern void cio_tsch(struct subchannel *sch);
 #else
 #define cio_is_console(schid) 0
-#define cio_get_console_subchannel() NULL
+static inline void cio_register_early_subchannels(void) {}
 #endif
 
 #endif