Consolidate sepolicy for twoshay and touchflow targets.

Bug: 187654303
Bug: 187795940
Bug: 198755236
Test: twoshay works on B5, R4, B3, P7; reflector works on O6
Change-Id: I04b98c3b42e886b1900150c175318095e559fa25
diff --git a/input/platform_app.te b/input/platform_app.te
new file mode 100644
index 0000000..17cc511
--- /dev/null
+++ b/input/platform_app.te
@@ -0,0 +1,2 @@
+allow platform_app touch_context_service:service_manager find;
+binder_call(platform_app, twoshay)