e1000e: implement 82577/579 MDI setting support

In order for e1000e to support MDI setting support via
ethtool this code is needed to allow setting the MDI state
via software.

This is in regards to the related ethtool patch and
fixes bugzilla.kernel.org bug 11998

Signed-off-by: Bruce W Allan <bruce.w.allan@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>