Initial commit: LSPi (LiangShanPi) project

GD32F470ZGT6 based project with full peripheral support:
- SDRAM (W9825G6KH) via EXMC
- LCD NT35510 (480x800) via EXMC NOR/PSRAM
- Flash (W25Q64) via SPI
- UART (USART0) debug console
- LED indicators
- CMSIS-DAP debug interface
- CMake + ARM GCC toolchain build system

bsp/hardware_init.h

@@ -0,0 +1,13 @@
+#ifndef __HARDWARE_INIT_H__
+#define __HARDWARE_INIT_H__
+
+#include "common_types.h"
+
+ret_code_t hardware_init(void);
+void system_clock_config(void);
+void peripheral_clock_enable(void);
+void gpio_init(void);
+void nvic_config(void);
+void mpu_config(void);
+
+#endif