drm-tests: Fix atomictest.multiple_planes failure on Intel.

Some platforms don't support DRM_FORMAT_XRGB8888 for cursor plane. e.g. IA
So use DRM_FORMAT_ARGB8888 as cursor format.

BUG=b:36681688
TEST=Ran these commands:
    emerge-{BOARD} drm-tests
    cros deploy --board $BOARD $IP drm-tests
    stop ui
    ./atomictest multiple_planes

Change-Id: Ic5095cd2267bdd2846dfba3d39e5b9d232acb1e2
Reviewed-on: https://chromium-review.googlesource.com/477650
Commit-Ready: Dongseong Hwang <dongseong.hwang@intel.com>
Tested-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
1 file changed