s390/memory hotplug: initialize storage keys

Add missing storage key initialization when memory comes online.
Didn't hurt until now, since the kernel always uses access key 0.

However for debugging purposes we sometimes use a different key
and it might be good if everything is properly initialized...

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

drivers/s390/char/sclp_cmd.c

@@ -352,7 +352,17 @@ out:
 
 static int sclp_assign_storage(u16 rn)
 {
-	return do_assign_storage(0x000d0001, rn);
+	unsigned long long start, address;
+	int rc;
+
+	rc = do_assign_storage(0x000d0001, rn);
+	if (rc)
+		goto out;
+	start = address = rn2addr(rn);
+	for (; address < start + rzm; address += PAGE_SIZE)
+		page_set_storage_key(address, PAGE_DEFAULT_KEY, 0);
+out:
+	return rc;
 }
 
 static int sclp_unassign_storage(u16 rn)