drm/virtio: enable prime mmap support

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190912114627.20176-1-kraxel@redhat.com

drivers/gpu/drm/virtio/virtgpu_drv.c

@@ -199,6 +199,7 @@ static struct drm_driver driver = {
 #endif
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+	.gem_prime_mmap = drm_gem_prime_mmap,
 	.gem_prime_import_sg_table = virtgpu_gem_prime_import_sg_table,
 
 	.gem_create_object = virtio_gpu_create_object,