drm/vmwgfx: add MODULE_DEVICE_TABLE so vmwgfx loads at boot

This will cause udev to load vmwgfx instead of waiting for X
to do it.

Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>