init: switch from /dev/keychord to /dev/input/

Replace deprecated /dev/keychord driver with /dev/input/ interface.
Will restrict which nodes are active and relevant, and try to mask
out any unreferenced inputs with EVIOCSMASK if available.

Test: manual, boot, check registered chord works
Bug: 64114943
Change-Id: I2bbf84a6e472d720f02282e10d56795b75ac62d1
diff --git a/init/keychords.h b/init/keychords.h
index 1c34098..689a3b5 100644
--- a/init/keychords.h
+++ b/init/keychords.h
@@ -22,8 +22,7 @@
 namespace android {
 namespace init {
 
-void add_service_keycodes(Service* svc);
-void keychord_init();
+void KeychordInit();
 
 }  // namespace init
 }  // namespace android