scsi: ufs: ufs-mediatek: Fix build error caused by use of sched_clock()

Add proper header for using sched_clock().

Link: https://lore.kernel.org/r/20211016005802.7729-3-stanley.chu@mediatek.com


Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>