加入外设头文件，移动中断编号

tb/sw/periph/i2c.h

@@ -0,0 +1,13 @@
+#ifndef _I2C_H_
+#define _I2C_H_
+
+#include <stdint.h>
+
+#define I2C_BASE 0x3040000U
+
+#define I2C_PRESCALER_LO 0x00  // low byte clock prescaler register
+#define I2C_PRESCALER_HI 0x04  // high byte clock prescaler register
+#define I2C_CONTROL      0x08  // control register
+#define I2C_DATA         0x0c  // write: transmit byte, read: receive byte
+#define I2C_CMD_STATUS   0x10  // write: command, read: status
+