scsi: ufs: ufs-mediatek: Fix power down spec violation

scsi: ufs: ufs-mediatek: Fix power down spec violation

BugLink: https://bugs.launchpad.net/bugs/1931896
[ Upstream commit c625b80b9d00f3546722cd77527f9697c8c4c911 ]

As per spec, e.g. JESD220E chapter 7.2, while powering off the UFS device,
RST_N signal should be between VSS(Ground) and VCCQ/VCCQ2. The power down
sequence after fixing:

Power down:

 1. Assert RST_N low

 2. Turn-off VCC

 3. Turn-off VCCQ/VCCQ2

Link: https://lore.kernel.org/r/1620813706-25331-1-git-send-email-peter.wang@mediatek.com
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>