[Ozone-Dri] Set DPMS to off when disabling a display

Need to turn it off to reduce the power used by the display when idling.

BUG=chrome-os-partner:35458
TEST=Wait for the displays to turn off and check with 'modetest -c' that the DPMS state is off

Review URL: https://codereview.chromium.org/877213005

Cr-Commit-Position: refs/heads/master@{#315111}

ui/ozone/platform/dri/native_display_delegate_dri.cc

@@ -200,6 +200,11 @@ bool NativeDisplayDelegateDri::Configure(const DisplaySnapshot& output,
       return false;
     }
   } else {
+    if (dri_output.dpms_property()) {
+      dri_->SetProperty(dri_output.connector(),
+                        dri_output.dpms_property()->prop_id, DRM_MODE_DPMS_OFF);
+    }
+
     if (!screen_manager_->DisableDisplayController(dri_output.crtc())) {
       VLOG(1) << "Failed to disable crtc=" << dri_output.crtc();
       return false;