drm: Reorganize drm_pending_event to support future event types [v2]

Place drm_event_vblank in a new union that includes that and a bare
drm_event structure. This will allow new members of that union to be
added in the future without changing code related to the existing vbl
event type.

Assignments to the crtc_id field are now done when the event is
allocated, rather than when delievered. This way, delivery doesn't
need to have the crtc ID available.

v2:
 * Remove 'dev' argument from create_vblank_event

	It wasn't being used anyways, and if we need it in the future,
	we can always get it from crtc->dev.

 * Check for MODESETTING before looking for crtc in queue_vblank_event

	UMS drivers will oops if we try to get a crtc, so make sure
	we're modesetting before we try to find a crtc_id to fill into
	the event.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit dc695b85fde88eca3ef3b03fcd82f15b6bc6e462)

drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c

@@ -549,8 +549,8 @@ static int vmw_stdu_crtc_page_flip(struct drm_crtc *crtc,
 
 		ret = vmw_event_fence_action_queue(file_priv, fence,
 						   &event->base,
-						   &event->event.tv_sec,
-						   &event->event.tv_usec,
+						   &event->event.vbl.tv_sec,
+						   &event->event.vbl.tv_usec,
 						   true);
 		vmw_fence_obj_unreference(&fence);
 	} else {