Move the STM32 eeprom driver from core to library

Avoid to build it when EEPROM is not used.

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

cores/arduino/board.h

@@ -12,7 +12,6 @@
 #include "digital_io.h"
 #include "dwt.h"
 #include "hw_config.h"
-#include "stm32_eeprom.h"
 #include "timer.h"
 #include "uart.h"
 

libraries/EEPROM/src/EEPROM.h

@@ -22,6 +22,9 @@
 #define EEPROM_h
 
 #include "Arduino.h"
+extern "C" {
+#include "utility/stm32_eeprom.h"
+}
 
 /***
     EERef class.