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>

drivers/gpu/drm/nouveau/nv04_display.c

@@ -140,7 +140,7 @@ nv04_display_destroy(struct drm_device *dev)
 			.crtc = crtc,
 		};
 
-		crtc->funcs->set_config(&modeset);
+		drm_mode_set_config_internal(&modeset);
 	}
 
 	/* Restore state */