wined3d: Wait for the command stream to finish before removing the context in adapter_no3d_uninit_3d().

Like we do in adapter_gl_uninit_3d() and adapter_vk_uninit_3d().
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>