scsi: ufs-mediatek: Keep VCC always-on for specific devices

For some devices which need extra delay after VCC power down, VCC shall be
kept always-on in some MediaTek UFS platforms to ensure the stability of
such devices because the extra delay may not be enough in those platforms.

Link: https://lore.kernel.org/r/20201207054955.24366-3-stanley.chu@mediatek.com


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