Recreate the surface textures after the scenegraph invalidation

When the scenegraph is invalidated we delete the surfaces texture.
Set the update flag to true so that when the scene graph is again
initialized and starts to draw a frame the textures will be recreated.

Change-Id: I2fb171e4bed517e48fa2311c22651150f3e605f7
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>