scsi: ufs: use WQ_HIGHPRI for gating work

Must have WQ_MEM_RECLAIM
``WQ_MEM_RECLAIM``
  All wq which might be used in the memory reclaim paths **MUST**
  have this flag set.  The wq is guaranteed to have at least one
  execution context regardless of memory pressure.

Bug: 158050260
Bug: 155410470
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
Link: https://lore.kernel.org/linux-scsi/20200915204532.1672300-3-jaegeuk@kernel.org/T/#u
Change-Id: I65f2608650fa3436503581a60ac539f85273a21e
(cherry picked from commit ceed5e02518f5cedc799f2f37bd30211243a7959)
Signed-off-by: Adam W. Willis <return.of.octobot@gmail.com>
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>

drivers/scsi/ufs/ufshcd.c

@@ -2992,8 +2992,8 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
 
 	snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_gating_%d",
 			hba->host->host_no);
-	hba->clk_gating.clk_gating_workq =
-		create_singlethread_workqueue(wq_name);
+	hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(wq_name,
+					WQ_MEM_RECLAIM | WQ_HIGHPRI);
 
 	gating->is_enabled = true;