Fix stm32f4 flash HW bug !

Note:

/*
       *     STM2F4xx (ST3240G) can't clear FLASH error flags (use google serach)
       *
       *   https://my.st.com/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/AllItems.aspx?RootFolder=%2
       *   Fpublic%2FSTe2ecommunities%2Fmcu%2FLists%2Fcortex_mx_stm32%2FSTM2F4xx%20(ST3240G)%20can
       *   't%20clear%20FLASH%20error%20flags
       *
       */
    #ifndef DONT_FIX_BUG
    LOG(LOG_DEBUG, "FLASH->SR (B) = 0x%08X \n", FLASH->SR);
    FLASH_ClearFlag(FLASH_FLAG_PGSERR | FLASH_FLAG_PGPERR |
                    FLASH_FLAG_PGAERR | FLASH_FLAG_WRPERR |
                    FLASH_FLAG_OPERR | FLASH_FLAG_EOP); // clear error status
    LOG(LOG_DEBUG, "FLASH->SR (A) = 0x%08X \n", FLASH->SR);
    #endif

Signed-off-by: cctsao1008 <chiacheng.tsao@gmail.com>