sfxge(4): fix build issue with PHY LED control enabled

Fixed build issue with the EFSYS_OPT_PHY_LED_CONTROL for Huntigton and
Medford.

Submitted by: Vijay Srivastava <vijays at solarflare.com>
Sponsored by: Solarflare Communications, Inc.
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D18110