scsi: ufs: add operation for the uic power mode change

Setting PA_PWRMode using DME_SET triggers the power mode
change. And then the result will be given by the HCS.UPMCRS.
This operation should be done atomically.

Change-Id: I3091de5fe9661ccbf31eda1721d1e8c367b8347f
Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Patch-mainline: linux-scsi@vger.kernel.org @ 2013/08/26, 14:40
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>