Add PHY module for re(4)

Add PHY module for re(4)

Changes to the original code:
- Turn on MIIF_IS_1000X so that mii_bmsr_media_to_anar() won't lie
- Enable auto-negotiation in rgephy_reset() so that ifconfig(8) will report
  correct media even when re(4) is not up

Obtained-from: FreeBSD
Patched-by: me and Gary Allan <dragonfly@gallan.plus.com>
Requested-by: Tomaz Borstnar <tomaz.borstnar@over.net>
Tested-by: Tomaz Borstnar <tomaz.borstnar@over.net>
	   Gary Allan <dragonfly@gallan.plus.com>
	   and me

# Thank Bill Paul and many other people for their work on this PHY module