Set default serial port back to 0.

Marlin/Configuration.h

 #define STRING_VERSION_CONFIG_H "2012-05-02" //Personal revision number for changes to THIS file.
 #define STRING_CONFIG_H_AUTHOR "erik" //Who made the changes.
 
+// SERIAL_PORT selects which serial port should be used for communication with the host.
+// This allows the connection of wireless adapters (for instance) to non-default port pins.
+// Serial port 0 is still used by the Arduino bootloader regardless of this setting.
+#define SERIAL_PORT 0
+
 // This determines the communication speed of the printer
 #define BAUDRATE 250000
 //#define BAUDRATE 115200
 // SF send wrong arc g-codes when using Arc Point as fillet procedure
 //#define SF_ARC_FIX
 
-
-// SERIAL_PORT selects which serial port should be used for communication with the host.
-// This allows the use of wireless adapters (for instance) which are connected to 
-// non-default serial port pins.
-#define SERIAL_PORT 2
-
-
 #include "Configuration_adv.h"
 #include "thermistortables.h"