graphics_Drm: use -a option to run atomic.

Use -a (automatic) option to run fast when not visually debugging
the output of the test. This speeds up atomic test.

BUG=chromium:828163
TEST=lab will test

Change-Id: I63b05c9fa29a510f618c90cc64c9534e2d39dc23
Reviewed-on: https://chromium-review.googlesource.com/1020880
Commit-Ready: Ilja H. Friedel <ihf@chromium.org>
Tested-by: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
diff --git a/client/site_tests/graphics_Drm/graphics_Drm.py b/client/site_tests/graphics_Drm/graphics_Drm.py
index ba3c9a7..8100a91 100644
--- a/client/site_tests/graphics_Drm/graphics_Drm.py
+++ b/client/site_tests/graphics_Drm/graphics_Drm.py
@@ -106,8 +106,8 @@
 drm_tests = {
     test.name: test
     for test in (
-        DrmTest('atomictest', 'atomictest -t all', min_kernel_version='4.4',
-                timeout=300),
+        DrmTest('atomictest', 'atomictest -a -t all', min_kernel_version='4.4',
+                timeout=120),
         DrmTest('drm_cursor_test'),
         DrmTest('linear_bo_test'),
         DrmTest('mmap_test', timeout=300),