Fix incorrect calculation of "ms" based waiting time in function
ufs_mtk_setup_clocks().

Link: https://lore.kernel.org/r/20200809055702.20140-1-stanley.chu@mediatek.com
Fixes: 9006e398 ("scsi: ufs-mediatek: Do not gate clocks if auto-hibern8 is not entered yet")
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>