block: Fix bdrv_all_delete_snapshot() error handling

The code to exit the loop after bdrv_snapshot_delete_by_id_or_name()
returned failure was duplicated. The first copy of it was too early so
that the AioContext lock would not be freed. This patch removes it so
that only the second, correct copy remains.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

block/snapshot.c

@@ -409,9 +409,6 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
         if (bdrv_can_snapshot(bs) &&
                 bdrv_snapshot_find(bs, snapshot, name) >= 0) {
             ret = bdrv_snapshot_delete_by_id_or_name(bs, name, err);
-            if (ret < 0) {
-                goto fail;
-            }
         }
         aio_context_release(ctx);
         if (ret < 0) {