drm-tests: track mapping size to be used for later unmap

This is to prepare for gbm_bo_get_plane_size deprecation.

BUG=b:282243659
TEST=emerge-$BOARD drm-tests

Change-Id: I8e8d56cad9ec86495717ec024d5d71d0099f603a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/drm-tests/+/4530682
Tested-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Dawn Han <dawnhan@google.com>
Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Commit-Queue: Yiwei Zhang <zzyiwei@chromium.org>
1 file changed