btrfs: open code read_fs_root

After the update to btrfs_get_fs_root, read_fs_root has become trivial
wrapper that can be open coded.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2020-05-15 19:35:57 +02:00
commit a820feb546