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/services/inputflinger/tests/Android.bp b/services/inputflinger/tests/Android.bp
index 6465cc9..8cb7194 100644
--- a/services/inputflinger/tests/Android.bp
+++ b/services/inputflinger/tests/Android.bp
@@ -48,4 +48,5 @@
         "libc++fs"
     ],
     require_root: true,
+    test_suites: ["device-tests"],
 }