Several ethernet drivers have been broken by the ethtool support because
the ioctl code used to power the interface up and down as needed. Rather
than add this to each driver call Jeff Garzik suggested we add hooks
for before/after ethtool processing.

This patch implements them which makes fixing the PM stuff easier,
as the epic100 patch to follow will show. It also cleans up the
via-velocity driver pm/ethtool logic a great deal. As per Jeff's
request the before handler is allowed to fail the operation.

--

The contribution herein included is a creation of Red Hat Inc. It is hereby
submitted under the license of the existing files and as a derivative work
thereof. I know of no reason for not having the right to submit the
work herein included.

(Bluff your way in legalese ;))