[S390] cio: Cleanup crw interface.

Eliminate the need for the machine check handler to call into
the common I/O layer directly by introducing an interface to
register handlers for crws per rsc.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

drivers/s390/cio/chsc.h

@@ -36,8 +36,6 @@ struct channel_path_desc {
 
 struct channel_path;
 
-extern void chsc_process_crw(void);
-
 struct css_general_char {
 	u64 : 41;
 	u32 aif : 1;     /* bit 41 */