remove workaround found in FreeBSD driver but not in Intel's official driver.
remove workaround found in FreeBSD driver but not in Intel's official
driver.

Fixes 82578DC from only being able to negotiate at 10baseT.

ok jsg@
please commit mikeb@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars