quota: avoid increasing DQST_LOOKUPS when iterating over dirty/inuse list

It is meaningless to increase DQST_LOOKUPS number while iterating
over dirty/inuse list, so just avoid it.

Link: https://lore.kernel.org/r/20190926083408.4269-1-cgxu519@zoho.com.cnSigned-off-by: Chengguang Xu <cgxu519@zoho.com.cn>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -595,7 +595,6 @@ int dquot_scan_active(struct super_block *sb,
 		/* Now we have active dquot so we can just increase use count */
 		atomic_inc(&dquot->dq_count);
 		spin_unlock(&dq_list_lock);
-		dqstats_inc(DQST_LOOKUPS);
 		dqput(old_dquot);
 		old_dquot = dquot;
 		/*
@@ -649,7 +648,6 @@ int dquot_writeback_dquots(struct super_block *sb, int type)
 			 * use count */
 			dqgrab(dquot);
 			spin_unlock(&dq_list_lock);
-			dqstats_inc(DQST_LOOKUPS);
 			err = sb->dq_op->write_dquot(dquot);
 			if (err) {
 				/*