drm/exynos: fix comment to exynos_drm_device_subdrv_prove call

subdrv_probe callback of virtual display driver will be
called by exynos_drm_device_subdrv_probe() to create crtc
and encoder/connector for virtual display driver.
So it fixes comments to exynos_drm_device_subdrv probe call.
Signed-off-by: NInki Dae <inki.dae@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -109,7 +109,7 @@ static int exynos_drm_load(struct drm_device *dev, unsigned long flags)
 	if (ret)
 		goto err_cleanup_vblank;
 
-	/* Probe non kms sub drivers. */
+	/* Probe non kms sub drivers and virtual display driver. */
 	ret = exynos_drm_device_subdrv_probe(dev);
 	if (ret)
 		goto err_unbind_all;