mailmap: Disambiguate between another author

.mailmap

@@ -4,4 +4,5 @@ Benjamin Klettbach <[email protected]>
 BtbN <[email protected]>
 John Bradley <[email protected]>
 HomeWorld <[email protected]> hwdro <[email protected]>
-Michael Fabian Dirks <[email protected]> <[email protected]>
+Michael Fabian Dirks <[email protected]> <[email protected]>
+Martell Malone <[email protected]>