platforms/drm: handle disabled outputs better
We must create render resources for disabled outputs so that the test can work properly, and then disable them again afterwards. So that the disabling doesn't fail we need to wait for idle before disabling them again.
A better solution would be to either do TEST_ONLY for the full configuration and do the commit with the respective outputs disabled and/or allocate crtcs more dynamically, so that we don't have to care if a disabled output would work. The first option didn't work properly on all hardware last time but could likely be backported to 5.23 if figured out, the second one will probably require too many changes to go in as a bufix.