[S390] locking problem with __cpcmd.

Changeset 740b5706 moved the protecting
spinlock from __cpcmd to cpcmd. Therefore vmcp can no longer use __cpcmd,
instead we have to use cpcmd.
Signed-off-by: NChristian Borntraeger <cborntra@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/vmcp.c

@@ -117,7 +117,7 @@ vmcp_write(struct file *file, const char __user * buff, size_t count,
 		return -ENOMEM;
 	}
 	debug_text_event(vmcp_debug, 1, cmd);
-	session->resp_size = __cpcmd(cmd, session->response,
+	session->resp_size = cpcmd(cmd, session->response,
 				     session->bufsize,
 				     &session->resp_code);
 	up(&session->mutex);