scsi: ufs-mediatek: Support option to disable auto-hibern8

Support an option to allow users to disable auto-hibern8 feature.

Instead, enable hibern8-during-clk-gating feature to keep similar power
consumption.

Link: https://lore.kernel.org/r/20201029115750.24391-5-stanley.chu@mediatek.com


Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>