scsi: ufs: ufs-mediatek: Support host power control

Add interfaces for controlling the host power to optimize the power
consumption in MediaTek UFS platforms.

Link: https://lore.kernel.org/r/20220623035052.18802-7-stanley.chu@mediatek.com


Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Po-Wen Kao <powen.kao@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>