[dbus] Do assign fallback mode correctly to avoid corruption

Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>

src/usb_moded-dbus.c

@@ -78,10 +78,9 @@ static DBusHandlerResult msg_handler(DBusConnection *const connection, DBusMessa
 
 		/* To the outside we want to keep CHARGING and CHARGING_FALLBACK the same */
 		if(!strcmp(MODE_CHARGING_FALLBACK, mode))
-			mode = strdup(MODE_CHARGING);
+			mode = MODE_CHARGING;
       		if((reply = dbus_message_new_method_return(msg)))
         		dbus_message_append_args (reply, DBUS_TYPE_STRING, &mode, DBUS_TYPE_INVALID);
-		free((void *)mode);
     	}
     	else if(!strcmp(member, USB_MODE_STATE_SET))
     	{