modesetting: Fix screen save issue when using atomic modeset

In atomic modeset case, the output's dpms property would not be updated
when exiting screen save.

Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
3 jobs for modeset in 6 minutes and 37 seconds (queued for 18 seconds)
latest
Status Name Job ID Coverage
  Docker Image
passed debian-testing #576583

00:00:46

 
  Build And Test
passed autotools-build-and-test #576584

00:05:50

passed meson-build-and-test #576585

00:02:05