msm: camera: Set timestamp type for the vb2 buffers

The timestamp type for the vb2 buffers are not initialiazed with
appropriate type which are resulting in kernel warning messages
whenever camera application is launched, hence set timestamp
type for the vb2 buffers to V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC

Change-Id: I66aa51d9f3c2978ee574da5d9b7b673a07ddee45
Signed-off-by: Lakshmi Narayana Kalavala <lkalaval@codeaurora.org>