add board: DshanMCU Pitaya Lite

[koendv]

Describe the PR
This PR adds support for DshanMCU Pitaya Lite and Blue Pill boards with MM32F3273 cpu.

Additional context
I have tested tinyusb on:

• DshanMCU Pitaya Lite with MM32F3273G8P
• WeAct Blue Pill boards with the STM32F103 replaced by a MM32F3273G6P

tinyusb works, but care has to be taken to choose the correct SYSCLK_FREQ.

For the MM32F3273 with a 12 MHz crystal, in tinyusb/hw/mcu/mindmotion/mm32sdk/mm32f327x/MM32F327x/Source/system_mm32f327x.c choose

#define SYSCLK_FREQ_XXMHz  (HSE_VALUE*8)      //96000000 based HSE_VALUE = 12000000

For the MM32F3273 with a 8 MHz crystal, choose

#define SYSCLK_FREQ_XXMHz  (HSE_VALUE*12)      //96000000 based HSE_VALUE = 8000000

Thank you for your useful software.

[hathach]

thank you very much for the PR, regarding the HSE_VALUE which is 12Mhz on some boards. I have updated the mm32sdk to add ifndef around the defined of SYSCLK_FREQ_XXMHz/SYSCLK_HSI_XXMHz and also add 1-DHSE_VALUE=` to board.mk that matches its hardware. This should solve this issue https://github.com/hathach/tinyusb/pull/1882/files#diff-d115a2b59f4f8d51aef8da0070cea68b35df06cb687b844eba59de2f7db7baa9R2

To be honest, mm32 isn't doing its work to maintain the driver. Requiring chaning the system_*.c file and header file to get the HSE_VALUE is a bit under par.