Sync clock using hwclock.

  Args:
    logger: logger object, used to write to SysLog and serial port.

def CallHwclock(logger):
  """Sync clock using hwclock.

  Args:
    logger: logger object, used to write to SysLog and serial port.
  """
  command = ['/sbin/hwclock', '--hctosys']
  try:
    subprocess.check_call(command)
  except subprocess.CalledProcessError:
    logger.warning('Failed to sync system time with hardware clock.')
  else:
    logger.info('Synced system time with hardware clock.')