* 为n32g45x添加硬件CRC支持 基于stm32的驱动文件进行改造,目前modbus的crc16和mpeg2的crc32测试正常
[bsp/n32g452xx] In drv_pwm.c, variable meaning is different with RT-Thread interface definition. Fixed and tested. [bsp/n32g452xx] Add support for UART4/UART5. [bsp/n32g452xx] In drv_gpio.c Modify "N32F10X_PIN_NUMBERS" to "N32G45X_PIN_NUMBERS".
1. remove gpio&uart INIT_BOARD_EXPORT 2. init gpio&uart in rt_hw_board_init 3. add clock driver
[add] N32G452 BSP