exynos-drm: add 85.5MHz pixel clock HDMI PHY config for Exynos4412

Configuration details from Samsung. This enables 1366x768@60Hz,
which also needs the horizontal blanking hack to work around a
mixer bug, which is now generalized to just look at vertical
resolution.

Signed-off-by: Daniel Drake <drake@endlessm.com>
Merge pull request #63 from dsd/odroid-3.8.y

exynos-drm: add 85.5MHz pixel clock HDMI PHY config for Exynos4412