drm: rockchip: Turn off VT switching on suspend

drm/rockchip already has support for disabling all displays on suspend
and enabling them on resume.

Disable automatic VT switching on suspend by the pm console tracking
layer.

Tested on veyron, used `echo mem > sys/power/state`
  => verified no VT switch
Reviewed-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NCaesar Wang <wxt@rock-chips.com>

drivers/gpu/drm/rockchip/rockchip_drm_fbdev.c

@@ -119,6 +119,9 @@ static int rockchip_drm_fbdev_create(struct drm_fb_helper *helper,
 	DRM_DEBUG_KMS("FB [%dx%d]-%d kvaddr=%p offset=%ld size=%d\n",
 		      fb->width, fb->height, fb->depth, rk_obj->kvaddr,
 		      offset, size);
+
+	fbi->skip_vt_switch = true;
+
 	return 0;
 
 err_drm_framebuffer_unref: