GitLab

Allow primary planes to not have to be the size of the mode. This lets
us configure a primary plane that's smaller than the current mode,
which will be useful for the underlay strategy.

This commit also adds a new option to ozone_demo to test the partial
primary plane functionality.

BUG=772239
TEST=ozone_demo --enable-drm-atomic --partial-primary-plane works on
    KBL or RK3399 boards showing red/blue pulsing square;
    ozone_demo --disable-drm-atomic --partial-primary-plane shows black
    screen but doesn't exit or crash.

Bug: 
Change-Id: Ie77b02848efca717dee465783c692333d2e6c988
Reviewed-on: https://chromium-review.googlesource.com/666000Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Commit-Queue: Kristian H. Kristensen <hoegsberg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517429}