Revert "fs: btrfs: fix false negatives in ROOT_ITEM search"

Per Pierre this change shouldn't have been applied as it was superseded
by "fs: btrfs: fix btrfs_search_tree invalid results" which is also
applied now as 1627e5e5.

This reverts commit 633967f9.

Signed-off-by: Tom Rini <trini@konsulko.com>