scsi: ufs: ufs-mediatek: Disable unused VCCQx power rails

Some MediaTek UFS platforms support different VCCQx power rails, for
example, both 1.2v and 1.8v VCCQx, in a single kernel image.

To optimize the system power consumption, provide a way to disable and
release the unused power rail during the device probing.

Link: https://lore.kernel.org/r/20220616053725.5681-12-stanley.chu@mediatek.com
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>