Fix _BV already defined warnings

Marlin/src/HAL/HAL_AVR/fastio_AVR.h

@@ -55,10 +55,6 @@
   #error "Pins for this chip not defined in Arduino.h! If you have a working pins definition, please contribute!"
 #endif
 
-#ifndef _BV
-  #define _BV(bit) (1UL << (bit))
-#endif
-
 /**
  * Magic I/O routines
  *

Marlin/src/HAL/HAL_DUE/HAL_Due.h

@@ -53,8 +53,6 @@
   #define MYSERIAL customizedSerial
 #endif
 
-#define _BV(bit) (1 << (bit))
-
 // We need the previous define before the include, or compilation bombs...
 #include "MarlinSerial_Due.h"
 

Marlin/src/HAL/HAL_LPC1768/include/arduino.h

@@ -38,8 +38,6 @@
 #define OUTPUT       0x01
 #define INPUT_PULLUP 0x02
 
-#define _BV(bit) (1 << (bit))
-
 #define E2END 0xFFF // EEPROM end address
 
 typedef uint8_t byte;

Marlin/src/HAL/HAL_STM32F1/HAL_Stm32f1.h

@@ -77,8 +77,6 @@
   #define MYSERIAL Serial3
 #endif
 
-#define _BV(bit) 	(1 << (bit))
-
 /**
  * TODO: review this to return 1 for pins that are not analog input
  */