video: Use boot clock for recording start time

Camera HAL3 uses boot time for buffer timestamp, rather
than system monotonic time. This leads to issues as
framework uses system monotonic time as reference start
time for timestamp adjustment.

Add change to use boot time for reference start time.

CRs-Fixed: 946735

Change-Id: Id0af9c8aed1a983095275ac03f7f59abc31594cc