scsi: ufs: core: Fix an error handler crash

scsi: ufs: core: Fix an error handler crash

The UFS error handler may be activated before SCSI scanning has started
and hence before hba->ufs_device_wlun has been set. Check the
hba->ufs_device_wlun pointer before using it.

Cc: Peter Wang <peter.wang@mediatek.com>
Cc: Nitin Rawat <nitin.rawat@oss.qualcomm.com>
Fixes: e23ef4f22db3 ("scsi: ufs: core: Fix error handler host_sem issue")
Fixes: f966e02ae521 ("scsi: ufs: core: Fix runtime suspend error deadlock")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: Nitin Rawat <nitin.rawat@oss.qualcomm.com>
Tested-by: Nitin Rawat <nitin.rawat@oss.qualcomm.com> #SM8750
Link: https://patch.msgid.link/20251204170457.994851-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>