boards/samr21-xpro:fix SPI_1 DIPO config

boards/samr21-xpro/include/periph_conf.h

@@ -178,7 +178,7 @@ static const pwm_conf_t pwm_config[] = {
 #define SPI_1_DEV          SERCOM5->SPI
 #define SPI_IRQ_1          SERCOM5_IRQn
 #define SPI_1_DOPO         (1)
-#define SPI_1_DIPO         (2)
+#define SPI_1_DIPO         (0)
 
 #define SPI_1_SCLK_DEV     PORT->Group[1]
 #define SPI_1_SCLK_PIN     (23)