scsi: ufs: host: mediatek: Handle clock scaling for high gear in PM flow

scsi: ufs: host: mediatek: Handle clock scaling for high gear in PM flow

Add clock scaling down for power management flow in the UFS Mediatek
driver. If clock scaling is disabled and fixed in high gear, ensure the
clock scales down during suspend and scales up again after resume to
support high gear.  This adjustment maintains proper power management.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Acked-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Link: https://patch.msgid.link/20250924094527.2992256-4-peter.wang@mediatek.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>