drm_hwcomposer: Use mode vrefresh if provided

Instead of always calculating the vrefresh from clock + resolution,
use vrefresh from the mode if its provided.

Bug: 25319209
Test: Tested on smaug, refresh reports 60Hz

Change-Id: I963ccb153d1856f5e45e4a1aa6fbd20b105d4a84
Signed-off-by: Sean Paul <seanpaul@chromium.org>
2 files changed