msm: VPU: Remove buffer timestamp translation

Buffer timestamps should be passed to firmware as is wihtout translation.
In the standard usage the timestamps correspond to timeval (seconds and
microseconds). But in other modes, they can be used as a simple counter,
which is made possible by removing the unnecessary translation.

Change-Id: I3ef1dde3e3a9bbaaa84771dee37fb7ae48e82738
Signed-off-by: Ahmed Abdul-Salam <aabdulsa@codeaurora.org>