drm-tests: Clear in_fence_fd when disabling plane

Otherwise the value from one test might persist to subsequent tests.

BUG=b:115333787
TEST=atomictest -t all passes on grunt

Change-Id: I9fba943ee3fb8a4c780e984c7fef881a9e5a1ee9
Reviewed-on: https://chromium-review.googlesource.com/1220290
Commit-Ready: Drew Davenport <ddavenport@chromium.org>
Tested-by: Drew Davenport <ddavenport@chromium.org>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
1 file changed