[S390] monwriter: fix return code handling

Fix return code handling within monwrite_new_hdr(). Return code handling
is everwhere implemented, the return code of the diagnose function was
just not passed.

Signed-off-by: Heiko Carstens <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

drivers/s390/char/monwriter.c

···
 {
 	struct monwrite_hdr *monhdr = &monpriv->hdr;
 	struct mon_buf *monbuf;
-	int rc;
+	int rc = 0;
 
 	if (monhdr->datalen > MONWRITE_MAX_DATALEN ||
 	    monhdr->mon_function > MONWRITE_START_CONFIG ||
···
 			mon_buf_count++;
 	}
 	monpriv->current_buf = monbuf;
-	return 0;
+	return rc;
 }
 
 static int monwrite_new_data(struct mon_private *monpriv)