Remove unused arg 'holder' from parse_subvol_options(), which has been
forgotten to be cleaned in the commit b99beb110e2d ("btrfs: split
parse_early_options() in two").
Signed-off-by: NTomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>