drm/virtio: drop resource_id argument.

We pass the obj anyway, so obj->hw_res_handle can be used instead
in virtio_gpu_object_attach() and virtio_gpu_cmd_create_resource().

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20181019061847.18958-6-kraxel@redhat.com