Don't crash on listener registrations.

This one was missed. If a binder transaction fails while trying to serve
a service notification, don't crash the hwservicemanager.

Bug: 34739804
Test: pass
Change-Id: Ia3e31c3909ef428591a7ba89331a819271112fe7
diff --git a/HidlService.cpp b/HidlService.cpp
index 532d426..d27ea5f 100644
--- a/HidlService.cpp
+++ b/HidlService.cpp
@@ -38,7 +38,9 @@
     mListeners.push_back(listener);
 
     if (mService != nullptr) {
-        listener->onRegistration(mInterfaceName, mInstanceName, true /* preexisting */);
+        auto ret = listener->onRegistration(
+            mInterfaceName, mInstanceName, true /* preexisting */);
+        ret.isOk(); // ignore
     }
 }