backports: handle struct ethtool_cmd MDI changes

backports: handle struct ethtool_cmd MDI changes

In kernel 3.7 struct ethtool_cmd received eth_tp_mdix and eth_tp_mdix_ctrl.
Address this by putting ifdef around the code using these struct components.

commit 6f6bbc186dc8e4e0c628db7decbd1a5e02cb5fd8
Author: Jesse Brandeburg <jesse.brandeburg@intel.com>
Date:   Thu Jul 26 02:30:53 2012 +0000

    ethtool.h: MDI setting support

git describe --contains 6f6bbc186dc8e4e0c628db7decbd1a5e02cb5fd8
v3.7-rc1~145^2~300^2~5

Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>