Merge pull request #7347 from fiveangle/at90usb_usbcon_unification

Remove extraneous USBCON defines for AT90USB boards

Marlin/pins_5DPRINT.h

 #define DEFAULT_MACHINE_NAME "Makibox"
 #define BOARD_NAME           "5DPrint D8"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true
 
 //

Marlin/pins_BRAINWAVE.h

 
 #define BOARD_NAME         "Brainwave"
 
-#define USBCON 646  // Disable MarlinSerial etc.
-
 //
 // Limit Switches
 //

Marlin/pins_BRAINWAVE_PRO.h

 
 #define BOARD_NAME         "Brainwave Pro"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true
 
 //

Marlin/pins_PRINTRBOARD.h

 
 #define BOARD_NAME         "Printrboard"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true
 
 // Disable JTAG pins so they can be used for the Extrudrboard

Marlin/pins_SAV_MKI.h

 #define DEFAULT_SOURCE_CODE_URL "https://github.com/fmalpartida/Marlin/tree/SAV-MkI-config"
 #define BOARD_NAME              "SAV MkI"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true
 
 //

Marlin/pins_TEENSY2.h

 
 #define BOARD_NAME         "Teensy++2.0"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true
 
 //

Marlin/pins_TEENSYLU.h

 
 #define BOARD_NAME         "Teensylu"
 
-#define USBCON 1286  // Disable MarlinSerial etc.
 #define LARGE_FLASH        true