Set the vr hwc vsync rate to match the native vsync

This simple modification reduces the motopho latency from 85ms to 65ms.
However, this is not a final solution, and we should continue to look
for how to address the issue of difference in vsync reporting.

Bug: 36493906
Test: Run motopho, latency is now much lower.
Change-Id: Id52689900a5fe58dfc9d7790b7c3746903380972