RUI Flash Write

RUI_RETURN_STATUS rui_flash_write(RUI_FLASH_MODE mode, uint8_t *str, uint32_t len);

@brief	This API is used to write user data to flash
@return	RUI_RETURN_STATUS
@param	uint8_t *str uint32_t len: For STM Series (RAK811/RAK4200/RAK4270) - Max 128 Bytes. For Nordic Series (RAK8212/RAK5010/RAK4600) - Max 64KB RUI_FLASH_MODE mode: user data or origin data
@module	RAK811, RAK4200, RAK4400, RAK4600, RAK5010 and RAK8212-M.