[zero] prepare variant for SPI and Wire board parameters

variants/arduino_zero/variant.h

@@ -129,6 +129,9 @@ static const uint8_t ATN = PIN_ATN;
 #define PIN_SPI_MISO         (22u)
 #define PIN_SPI_MOSI         (23u)
 #define PIN_SPI_SCK          (24u)
+#define PERIPH_SPI           sercom4
+#define PAD_SPI_TX           SPI_PAD_2_SCK_3
+#define PAD_SPI_RX           SERCOM_RX_PAD_0
 
 static const uint8_t SS	  = PIN_A2 ;	// SERCOM4 last PAD is present on A2 but HW SS isn't used. Set here only for reference.
 static const uint8_t MOSI = PIN_SPI_MOSI ;
@@ -142,6 +145,8 @@ static const uint8_t SCK  = PIN_SPI_SCK ;
 
 #define PIN_WIRE_SDA         (20u)
 #define PIN_WIRE_SCL         (21u)
+#define PERIPH_WIRE          sercom3
+#define WIRE_IT_HANDLER      SERCOM3_Handler
 
 /*
  * USB