drm: encapsulate crtc->set_config calls

With refcounting we need to adjust framebuffer refcounts at each
callsite - much easier to do if they all call the same little helper
function.

Reviewed-by: Rob Clark <rob@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index 161f8b2..07dfd82 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -829,7 +829,7 @@
 
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 		set.crtc = crtc;
-		ret = crtc->funcs->set_config(&set);
+		ret = drm_mode_set_config_internal(&set);
 		WARN_ON(ret != 0);
 	}