Btrfs: remove obsolete btrfs_next_leaf call from __resolve_indirect_ref

When resolving indirect refs, we used to call btrfs_next_leaf in case we
didn't find an exact match. While we should find exact matches most of the
time, in case we don't, we must continue searching. Treating those matches
differently depending on the level we're searching doesn't make sense.

Even worse, we might end up searching for a key larger than the largest, in
which case there is no next_leaf and subsequent jobs would fail. This commit
drops the bogous lines.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>