[S390] cio: fix storage key handling

Some parts of cio do not shift PAGE_DEFAULT_KEY correctly and end up
with an incorrect key in their data structures.
Since the default key is zero this doesn't really matter. However if
somebody would use key-controlled protection for debugging purposes
it would be quite helpful if all of this would work as expected.

Also remove a stale declaration.

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

drivers/s390/cio/chsc.c

@@ -574,7 +574,7 @@ int __chsc_do_secm(struct channel_subsystem *css, int enable, void *page)
 	secm_area->request.length = 0x0050;
 	secm_area->request.code = 0x0016;
 
-	secm_area->key = PAGE_DEFAULT_KEY;
+	secm_area->key = PAGE_DEFAULT_KEY >> 4;
 	secm_area->cub_addr1 = (u64)(unsigned long)css->cub_addr1;
 	secm_area->cub_addr2 = (u64)(unsigned long)css->cub_addr2;