Add TEST_MAPPING for input-related code

For better presubmit coverage, include all input-related code into
TEST_MAPPING files.

Bug: 167947085
Test: cd frameworks/native/services/inputflinger && atest

Change-Id: I7ba46c872c917deb8dfc0c17be4662b9caeacf13
diff --git a/libs/input/tests/Android.bp b/libs/input/tests/Android.bp
index 44147a5..b23aade 100644
--- a/libs/input/tests/Android.bp
+++ b/libs/input/tests/Android.bp
@@ -30,7 +30,8 @@
         "liblog",
         "libui",
         "libutils",
-    ]
+    ],
+    test_suites: ["device-tests"],
 }
 
 // NOTE: This is a compile time test, and does not need to be