Exynos decoder: workaround for wrong MFC output format.

EVDA currently uses NV12MT_16X16 (tiled) format for MFC output, while EVEA
uses NV12M (non-tiled) format. There appears to be a MFC driver or firmware
bug when VP8 decode and H264 encode run concurrently.

Workaround is to force EVDA to use non-tiled format (NV12M) so that MFC
output format is the same for both EVEA and EVDA.

BUG=302870
TEST=verify corruption is fixed when tab casting VP8 playback, AND hardware decoder is used.
R=scherkus@chromium.org

Review URL: https://codereview.chromium.org/25758003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226912 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226912