scsi: ufs: ufs-mediatek: Add stage information for ref-clk control

Add "PRE_CHANGE" and "POST_CHANGE" information for ref-clk control to
precisely configure the low-power state of the parent of ref-clk.

Link: https://lore.kernel.org/r/20220623035052.18802-5-stanley.chu@mediatek.com


Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>