btrfs: remove unused arg from parse_subvol_options()

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: Tomohiro Misono <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/super.c

@@ -948,7 +948,7 @@ out:
  * The value is later passed to mount_subvol()
  */
 static int btrfs_parse_subvol_options(const char *options, fmode_t flags,
-		void *holder, char **subvol_name, u64 *subvol_objectid)
+		char **subvol_name, u64 *subvol_objectid)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *opts, *orig, *p;
@@ -1667,7 +1667,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
 	if (!(flags & SB_RDONLY))
 		mode |= FMODE_WRITE;
 
-	error = btrfs_parse_subvol_options(data, mode, fs_type,
+	error = btrfs_parse_subvol_options(data, mode,
 					  &subvol_name, &subvol_objectid);
 	if (error) {
 		kfree(subvol_name);