drm_hwcomposer: Use atomic modeset to set crtc timing

drm_hwcomposer: Use atomic modeset to set crtc timing

Use the new drm blob ioctl and atomic modeset properties to
do atomic modesetting, as opposed to the old setCrtc call.

This allows us to set timing as soon as the system layer requests
a new active config, as opposed to delaying it until we have
an fb. Aside from reducing complexity, this should help with
event control requests as we'll be able to service them with
hw vblanks instead of synthesized sleeps.

Change-Id: I9c80d44f52f52881a3a25b2ae518973d468bc110
Signed-off-by: Sean Paul <seanpaul@chromium.org>