I2C slave support for Metro M4

Author: JordanMajd

variants/metro_m4/variant.h

@@ -159,6 +159,10 @@ static const uint8_t SCK  = PIN_SPI_SCK ;
 #define PIN_WIRE_SCL         (23u)
 #define PERIPH_WIRE          sercom5
 #define WIRE_IT_HANDLER      SERCOM5_Handler
+#define WIRE_IT_HANDLER_0    SERCOM5_0_Handler
+#define WIRE_IT_HANDLER_1    SERCOM5_1_Handler
+#define WIRE_IT_HANDLER_2    SERCOM5_2_Handler
+#define WIRE_IT_HANDLER_3    SERCOM5_3_Handler
 
 static const uint8_t SDA = PIN_WIRE_SDA;
 static const uint8_t SCL = PIN_WIRE_SCL;