[PATCH] forcedeth: add ethtool get/set_settings support

The patch adds ethtool get_ and set_settings support to the forcedeth nic
driver. This allows to force a certain link speed with ethtool -s.

Supported link speeds: 10 HD&FD, 100 HD&FD, 1000 FD

1000 HD is not supported (probably a hardware restriction), 1000 FD is
only supported with autonegotiation enabled.

Changelog:
- Code reorganization: move ethtool functions further down in forcedeth.c
  (no code changes within the existing ethtool functions)
- add support for setting the link setting bits in the nic with
autodetection in the PHY disabled (i.e. use a netdev_priv() variable
instead of querying the PHY)
- implement get_settings and set_settings ethtool functions.
Signed-Off-By: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>