compositor-drm: run finish_frame when dpms is turned off in update_complete

A output repaint loop isn't scheduled beacuse the output repaint_status
is AWAITING_COMPLETION when dmps is turned off in update_complete().
Therefore, the display attached to the output is remain inactive even if
weston wakes up. By going through finish_frame, the output
repaint_status is fixed to correct status.

Signed-off-by: Tomohito Esaki <etom@igel.co.jp>

libweston/backend-drm/drm.c

@@ -1933,7 +1933,6 @@ drm_output_update_complete(struct drm_output *output, uint32_t flags,
 		output->dpms_off_pending = 0;
 		drm_output_get_disable_state(pending, output);
 		drm_pending_state_apply_sync(pending);
-		return;
 	} else if (output->state_cur->dpms == WESTON_DPMS_OFF &&
 	           output->base.repaint_status != REPAINT_AWAITING_COMPLETION) {
 		/* DPMS can happen to us either in the middle of a repaint