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

[ Upstream commit 05848db2083d4f232e84e385845dcd98d5c511b2 ]

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.cn


Signed-off-by: Chengguang Xu <cgxu519@zoho.com.cn>
Signed-off-by: Jan Kara <jack@suse.cz>
Stable-dep-of: dabc8b207566 ("quota: fix dqput() to follow the guarantees dquot_srcu should provide")
Signed-off-by: Sasha Levin <sashal@kernel.org>