3c59x: fix duplex configuration

A special sequence of ifconfig up/down and plug/unplug the cable can break
the duplex configuration of the driver.

Setting
vp->mii.full_duplex = vp->full_duplex
in vortex_up should fix this.

Addresses Bug 8575 3c59x duplex configuration broken
http://bugzilla.kernel.org/show_bug.cgi?id=8575



Cc: Martin Buck <mb-tmp-ohtmvyyn.xreary.bet@gromit.dyndns.org>
Signed-off-by: Steffen Klassert <klassert@mathematik.tu-chemnitz.de>
Cc: Natalie Protasevich <protasnb@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>