Pass reference to finishKey

Since the parameter is assumed to be non-null, pass it by reference.

Bug: 274058082
Test: m libinput_tests && $ANDROID_HOST_OUT/nativetest64/libinput_tests/libinput_tests
Change-Id: Iedf8970a57e4463e6addc8ee1013feb3ee60c009
diff --git a/include/input/KeyCharacterMap.h b/include/input/KeyCharacterMap.h
index c67310e..9f1c0e2 100644
--- a/include/input/KeyCharacterMap.h
+++ b/include/input/KeyCharacterMap.h
@@ -227,7 +227,7 @@
         status_t parseMapKey();
         status_t parseKey();
         status_t parseKeyProperty();
-        status_t finishKey(Key* key);
+        status_t finishKey(Key& key);
         status_t parseModifier(const std::string& token, int32_t* outMetaState);
         status_t parseCharacterLiteral(char16_t* outCharacter);
     };