[autotest] Make suite:storagequal run on branch>=31

The test suite was introduced crosreview.com/64360.
Branches older than R31 won't have the test suite.
Change suite_scheduler.ini to make it run only on branch>=31

BUG=chromium:306857
TEST=None

Change-Id: I53be07818d225caf38fcaeed9da9fe2413db515d
Reviewed-on: https://chromium-review.googlesource.com/173589
Reviewed-by: Alex Miller <milleral@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
diff --git a/suite_scheduler.ini b/suite_scheduler.ini
index 6dbe548..f53eef5 100644
--- a/suite_scheduler.ini
+++ b/suite_scheduler.ini
@@ -35,7 +35,7 @@
 [WeeklyStoraqequal]
 run_on: weekly
 suite: storagequal
-branch_specs: >=R30
+branch_specs: >=R31
 pool: suites
 
 [NightlyGraphics]