btrfs: introduce item_nr token variant helpers
The last remaining place where we have the pattern of
item = btrfs_item_nr(slot)
<do something with the item>
are the token helpers. Handle this by introducing token helpers that
will do the btrfs_item_nr() work inside of the helper itself, and then
convert all users of the btrfs_item token helpers to the new _nr()
variants.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>