InputMapper: pass RawEvent references instead of pointers

We never pass null values here, so changing to references makes this
clearer.

Change-Id: I82d5359e244a93560bcbef477c89fef016168abb
Test: atest inputflinger_test
Test: m checkinput
Test: manually test basic functionality on a multi-touch screen, touchpad, mouse, and drawing tablet
Bug: 245989146
Flag: EXEMPT refactor
diff --git a/services/inputflinger/tests/fuzzers/TouchpadInputFuzzer.cpp b/services/inputflinger/tests/fuzzers/TouchpadInputFuzzer.cpp
index 643e8b9..c620032 100644
--- a/services/inputflinger/tests/fuzzers/TouchpadInputFuzzer.cpp
+++ b/services/inputflinger/tests/fuzzers/TouchpadInputFuzzer.cpp
@@ -176,7 +176,7 @@
                 },
                 [&]() -> void {
                     RawEvent event = getFuzzedRawEvent(*fdp);
-                    std::list<NotifyArgs> unused = mapper.process(&event);
+                    std::list<NotifyArgs> unused = mapper.process(event);
                 },
         })();
     }