e1000e: 82579: workaround for link drop issue

When connected to certain switches, the 82579 PHY might drop link
unexpectedly.  Work around the issue by setting the Mean Square Error
higher than the hardware default.

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