minigbm: drv_bo_flush --> drv_bo_flush_or_unmap

There's no flush or invalidate mechnaism with the DRI interface,
so we'll have to support mapping and unmapping.

BUG=b:72972511
TEST=gbmtest passes in CQ

Change-Id: If3aef651f8549544ed4ed499e17f7f99c597974c
Reviewed-on: https://chromium-review.googlesource.com/990892
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Satyajit Sahu <satyajit.sahu@amd.com>
Reviewed-by: Joe Kniss <djmk@google.com>
Reviewed-by: Satyajit Sahu <satyajit.sahu@amd.com>
diff --git a/drv.h b/drv.h
index 2271a9f..09aa33f 100644
--- a/drv.h
+++ b/drv.h
@@ -130,7 +130,7 @@
 
 int drv_bo_invalidate(struct bo *bo, struct mapping *mapping);
 
-int drv_bo_flush(struct bo *bo, struct mapping *mapping);
+int drv_bo_flush_or_unmap(struct bo *bo, struct mapping *mapping);
 
 uint32_t drv_bo_get_width(struct bo *bo);