scsi: ufs: add cpu-dma latency PM QOS request

Add PM QOS cpu-dma latency request to the driver.
Latency parameter value is taken from the device tree node
using an optional parameter 'qcom,cpu-dma-latency-us'.
Unless specified, a default of 200us is used.

Change-Id: I3e10da9e65fc7324897c866b0c2a40cc5e6ca070
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
[subhashj@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
[venkatg@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>