drm-tests: Fix issue related to multi-plane buffer objects

When a single buffer represents a multi-plane format, the
mmap() length argument needs to be modified.

CQ-DEPEND=CL:360905

BUG=chromium:616275
TEST=plane_test (defaults to NV12)

Change-Id: Ic404de043803b65d5336d693a43fbbfe2861c8f0
Reviewed-on: https://chromium-review.googlesource.com/360918
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>
1 file changed