[Portenta_SDCARD] Mutex is not released on deinit failure

[trik]

  int SDMMCBlockDevice::deinit()
  {
    lock();
    _sd_state = BSP_SD_DeInit ();
    if(_sd_state != MSD_OK) {
        debug_if (SD_DBG, "SD card deinitialization failed\n");
        return SD_BLOCK_DEVICE_ERROR;
    }