SCUMM: Fix Duplicate Branches GCC Compiler Warning

engines/scumm/scumm.cpp

@@ -369,6 +369,10 @@ ScummEngine::ScummEngine(OSystem *syst, const DetectorResult &dr)
 	// Steam Win and Mac versions share the same DOS data files.
 	bool isSteamVersion = Common::String(_game.preferredTag).equalsIgnoreCase("steam");
 
+	// defaults
+	_screenWidth = 320;
+	_screenHeight = 200;
+
 	if (_game.platform == Common::kPlatformFMTowns && _game.version == 3) {	// FM-TOWNS V3 games originally use 320x240, and we have an option to trim to 200
 		_screenWidth = 320;
 		if (ConfMan.getBool("trim_fmtowns_to_200_pixels"))
@@ -386,9 +390,6 @@ ScummEngine::ScummEngine(OSystem *syst, const DetectorResult &dr)
 	} else if (!isSteamVersion && _useMacScreenCorrectHeight && _game.platform == Common::kPlatformMacintosh && _game.version >= 3) {
 		_screenWidth = 320;
 		_screenHeight = 200;
-	} else {
-		_screenWidth = 320;
-		_screenHeight = 200;
 	}
 
 #ifndef DISABLE_TOWNS_DUAL_LAYER_MODE