scsi: ufs: host: mediatek: Support clock scaling with Vcore binding

Add support for clock scaling with Vcore binding:

 1. Parse the DTS setting for Vcore voltage.

 2. Set the Vcore voltage to the DTS-specified value before scaling up.

 3. Reset the Vcore voltage to the default setting after scaling down.

These changes ensure that the Vcore voltage is appropriately managed
during clock scaling operations to maintain system stability and
performance.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Link: https://lore.kernel.org/r/20250722030841.1998783-9-peter.wang@mediatek.com


Reviewed-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>