d3d12: Don't try to create a RTV or DSV when it's not supported
It is save to return a NULL surface here, because the framebuffer this surface would be bound to would be reported as incomplete by the same texture support test we use here to skip creating the surface.
Fixes: KHR-GL32.packed_pixels.varied_rectangle.rgb9_e5 KHR-GL32.packed_pixels.rectangle.rgb9_e5