modesetting: Disable crtc if no output attached

On some platforms, i915 require to disable crtc for making hotplug
continue to work.

drm/intel#2602
4 jobs for disable-crtcs-when-no-output in 4 minutes and 26 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Docker Image
passed #5670460
debian-buster

00:00:09

 
  Build And Test
passed #5670461
autotools

00:04:16

passed #5670462
meson

00:01:30

passed #5670463
meson-noglamor

00:00:45