Add test config to bootstat_tests

This change allows TradeFederation to run the test directly.
Refer to b/35882476 for design and discussion of this change.

Bug: 35882476
Test: local test
tradefed.sh run template/local --template:map test=bootstat_tests

Change-Id: I3bc2fa19faebe21f6faf8b81e206ea1581918344
diff --git a/bootstat/Android.bp b/bootstat/Android.bp
index 95c9af5..bc90a6e 100644
--- a/bootstat/Android.bp
+++ b/bootstat/Android.bp
@@ -74,6 +74,7 @@
 // -----------------------------------------------------------------------------
 cc_test {
     name: "bootstat_tests",
+    test_suites: ["device-tests"],
     defaults: ["bootstat_defaults"],
     host_supported: true,
     static_libs: [