scsi: ufs: core: Allow host driver to disable wb toggling during clock scaling

Mediatek UFS does not want to toggle write booster during clock scaling.
Permit host driver to disable wb toggling during clock scaling.

Introduce a flag UFSHCD_CAP_WB_WITH_CLK_SCALING to decouple WB and clock
scaling.  UFSHCD_CAP_WB_WITH_CLK_SCALING is only valid when
UFSHCD_CAP_CLK_SCALING is set. Just like UFSHCD_CAP_HIBERN8_WITH_CLK_GATING
is valid only when UFSHCD_CAP_CLK_GATING set.

Set UFSHCD_CAP_WB_WITH_CLK_SCALING for qcom to compatible legacy design at
the same time.

Link: https://lore.kernel.org/r/20220804025422.18803-1-peter.wang@mediatek.com


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