s390/crypt: fix missing unlock in ctr_paes_crypt on error path

The ctr mode of protected key aes uses the ctrblk page if the
ctrblk_lock could be acquired. If the protected key has to be
reestablished and this operation fails the unlock for the
ctrblk_lock is missing. Add it.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/crypto/paes_s390.c

@@ -474,10 +474,13 @@ static int ctr_paes_crypt(struct blkcipher_desc *desc, unsigned long modifier,
 			ret = blkcipher_walk_done(desc, walk, nbytes - n);
 		}
 		if (k < n) {
-			if (__ctr_paes_set_key(ctx) != 0)
+			if (__ctr_paes_set_key(ctx) != 0) {
+				if (locked)
+					spin_unlock(&ctrblk_lock);
 				return blkcipher_walk_done(desc, walk, -EIO);
 			}
 		}
+	}
 	if (locked)
 		spin_unlock(&ctrblk_lock);
 	/*