feat(ch32f20x): add support of ch32f20x

hw/bsp/ch32f20x/ch32f20x_it.h

@@ -0,0 +1,25 @@
+/********************************** (C) COPYRIGHT *******************************
+* File Name          : ch32f20x_it.h
+* Author             : WCH
+* Version            : V1.0.0
+* Date               : 2021/08/08
+* Description        : This file contains the headers of the interrupt handlers.
+*********************************************************************************
+* Copyright (c) 2021 Nanjing Qinheng Microelectronics Co., Ltd.
+* Attention: This software (modified or not) and binary are used for
+* microcontroller manufactured by Nanjing Qinheng Microelectronics.
+*******************************************************************************/
+#ifndef __CH32F20xIT_H
+#define __CH32F20xIT_H
+
+#include "ch32f20x.h"
+
+void NMI_Handler(void);
+void HardFault_Handler(void);
+void MemManage_Handler(void);
+void BusFault_Handler(void);
+void UsageFault_Handler(void);
+void DebugMon_Handler(void);
+
+
+#endif /* __CH32F20xIT_H */