minigbm: add bo import callback

Some drivers may want to import their own private data,
so let's add a driver callback.

BUG=none
TEST=minigbm builds, gbmtest

Change-Id: I96c06a84446c9be4ac3f5f858094c500d43a077f
Reviewed-on: https://chromium-review.googlesource.com/424934
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
diff --git a/nouveau.c b/nouveau.c
index 89122da..e0d5954 100644
--- a/nouveau.c
+++ b/nouveau.c
@@ -25,5 +25,6 @@
 	.init = nouveau_init,
 	.bo_create = drv_dumb_bo_create,
 	.bo_destroy = drv_dumb_bo_destroy,
+	.bo_import = drv_prime_bo_import,
 	.bo_map = drv_dumb_bo_map,
 };