Support Buffer length for SAMD21E series

As the title says..

Author: clavisound

src/SparkFun_External_EEPROM.h

@@ -40,7 +40,7 @@
 #define I2C_BUFFER_LENGTH_RX BUFFER_LENGTH // I2C_BUFFER_LENGTH is defined in Wire.H
 #define I2C_BUFFER_LENGTH_TX BUFFER_LENGTH
 
-#elif defined(__SAMD21G18A__)
+#elif defined(__SAMD21G18A__) || defined(__SAMD21E18A__)
 
 #define I2C_BUFFER_LENGTH_RX SERIAL_BUFFER_SIZE // SAMD21 uses RingBuffer.h
 #define I2C_BUFFER_LENGTH_TX SERIAL_BUFFER_SIZE