btrfs: change return type to bool in btrfs_extent_readonly

btrfs_extent_readonly() checks if the block group is readonly, the bool
return type should be used.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
1 file changed