btrfs: remove pointless out labels from free-space-cache.c

btrfs: remove pointless out labels from free-space-cache.c

Some functions (update_cache_item(), find_free_space(), trim_bitmaps(),
btrfs_remove_free_space() and cleanup_free_space_cache_v1()) have an 'out'
label that does nothing but return, making it pointless. Simplify this by
removing the label and returning instead of gotos plus setting the 'ret'
variable.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>