Inspired by the mailing-list posting [1], this commit removes the
MAC/PHY reset for all Intel cards and effectively prevents the bandwidth
drop to 10 MBit/s (e.g., on i217lm). I understand it as preliminary fix
for practical reasons - a real fix would be to update the ipxe port and
monitor for more postings like the one mentioned.
[1] http://lists.ipxe.org/pipermail/ipxe-devel/2015-December/004511.html
