drm/armada: remove armada_drm_plane_work_cancel() return value

armada_drm_plane_work_cancel()'s returned work structure is never used
or referenced, so it's pointless returning it.  It's also pointless
because the caller doesn't have a clue what kind of work structure it
is.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

drivers/gpu/drm/armada/armada_crtc.c

@@ -254,15 +254,13 @@ int armada_drm_plane_work_wait(struct armada_plane *plane, long timeout)
 	return wait_event_timeout(plane->frame_wait, !plane->work, timeout);
 }
 
-struct armada_plane_work *armada_drm_plane_work_cancel(
-	struct armada_crtc *dcrtc, struct armada_plane *plane)
+void armada_drm_plane_work_cancel(struct armada_crtc *dcrtc,
+	struct armada_plane *dplane)
 {
-	struct armada_plane_work *work = xchg(&plane->work, NULL);
+	struct armada_plane_work *work = xchg(&dplane->work, NULL);
 
 	if (work)
 		drm_crtc_vblank_put(&dcrtc->crtc);
-
-	return work;
 }
 
 static int armada_drm_crtc_queue_frame_work(struct armada_crtc *dcrtc,

drivers/gpu/drm/armada/armada_crtc.h

@@ -62,8 +62,8 @@ int armada_drm_plane_init(struct armada_plane *plane);
 int armada_drm_plane_work_queue(struct armada_crtc *dcrtc,
 	struct armada_plane *plane, struct armada_plane_work *work);
 int armada_drm_plane_work_wait(struct armada_plane *plane, long timeout);
-struct armada_plane_work *armada_drm_plane_work_cancel(
-	struct armada_crtc *dcrtc, struct armada_plane *plane);
+void armada_drm_plane_work_cancel(struct armada_crtc *dcrtc,
+	struct armada_plane *plane);
 void armada_drm_plane_calc_addrs(u32 *addrs, struct drm_framebuffer *fb,
 	int x, int y);