quota: minor code cleanup for v1_format_ops

It's not a functinal change, it's just for keeping
consistent coding style.

Link: https://lore.kernel.org/r/20191010130924.17697-1-cgxu519@mykernel.netSigned-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/quota_v1.c

@@ -217,7 +217,6 @@ static const struct quota_format_ops v1_format_ops = {
 	.check_quota_file	= v1_check_quota_file,
 	.read_file_info		= v1_read_file_info,
 	.write_file_info	= v1_write_file_info,
-	.free_file_info		= NULL,
 	.read_dqblk		= v1_read_dqblk,
 	.commit_dqblk		= v1_commit_dqblk,
 };