scsi: ufs: core: Start the RTC update work later

The RTC update work involves runtime resuming the UFS controller. Hence,
only start the RTC update work after runtime power management in the UFS
driver has been fully initialized. This patch fixes the following kernel
crash:

Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Workqueue: events ufshcd_rtc_work
Call trace:
_raw_spin_lock_irqsave+0x34/0x8c (P)
pm_runtime_get_if_active+0x24/0x9c (L)
pm_runtime_get_if_active+0x24/0x9c
ufshcd_rtc_work+0x138/0x1b4
process_one_work+0x148/0x288
worker_thread+0x2cc/0x3d4
kthread+0x110/0x114
ret_from_fork+0x10/0x20

Reported-by: Neil Armstrong <[e-mail]>
Closes: https://lore.kernel.org/linux-scsi/[e-mail]/
Fixes: 6bf999e0eb41 ("scsi: ufs: core: Add UFS RTC support")
Cc: Bean Huo <[e-mail]>
Cc: [e-mail]
Signed-off-by: Bart Van Assche <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Peter Wang <[e-mail]>
Reviewed-by: Bean Huo <[e-mail]>
Tested-by: Neil Armstrong <[e-mail]> # on SM8650-HDK
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/ufs/core/ufshcd.c

···
 		ufshcd_init_clk_scaling_sysfs(hba);
 	}
 
+	/*
+	 * The RTC update code accesses the hba->ufs_device_wlun->sdev_gendev
+	 * pointer and hence must only be started after the WLUN pointer has
+	 * been initialized by ufshcd_scsi_add_wlus().
+	 */
+	schedule_delayed_work(&hba->ufs_rtc_update_work,
+			      msecs_to_jiffies(UFS_RTC_UPDATE_INTERVAL_MS));
+
 	ufs_bsg_probe(hba);
 	scsi_scan_host(hba->host);
 
···
 	ufshcd_force_reset_auto_bkops(hba);
 
 	ufshcd_set_timestamp_attr(hba);
-	schedule_delayed_work(&hba->ufs_rtc_update_work,
-			      msecs_to_jiffies(UFS_RTC_UPDATE_INTERVAL_MS));
 
 	/* Gear up to HS gear if supported */
 	if (hba->max_pwr_info.is_valid) {