btrfs: make the uptodate argument of io_ctl_add_pages() boolean

Make the uptodate argument of io_ctl_add_pages() boolean.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>