scsi: ufs: Fix ufs power down/on specs violation

As per specs, while powering off/on the ufs device, RST_N signal
and REF_CLK signal should be between VSS(Ground) and VCCQ.

we should follow below sequence of events during power down and
power on:

Power down:
1. Turn-off REF_CLK
2. Assert RST_N low
3. Turn-off VCC
4. Turn-off VCCQ.

power on:
1. Turn-on VCC
2. Turn-on VCCQ
3. Turn-On REF_CLK
4. Deassert RST_N high.

Change-Id: I08c2646b52ed6b39f092c31f18df280063f67d86
Signed-off-by: Nitin Rawat <nitirawa@codeaurora.org>
Signed-off-by: Ziqi Chen <ziqichen@codeaurora.org>
Signed-off-by: Qing Wang <qinw@codeaurora.org>