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/i2c/ch7006_drv.c

@@ -364,7 +364,7 @@ static int ch7006_encoder_set_property(struct drm_encoder *encoder,
 				.crtc = crtc,
 			};
 
-			crtc->funcs->set_config(&modeset);
+			drm_mode_set_config_internal(&modeset);
 		}
 	}