scsi: ufs: host: mediatek: Fix shutdown/suspend race condition

scsi: ufs: host: mediatek: Fix shutdown/suspend race condition

Address a race condition between shutdown and suspend operations in the
UFS Mediatek driver. Before entering suspend, check if a shutdown is in
progress to prevent conflicts and ensure system stability.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Acked-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Link: https://patch.msgid.link/20250924094527.2992256-6-peter.wang@mediatek.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>