igb: Workaround for global device reset problem on 82580.

Due to a hw errata, the global device reset doesn't always work on 82580
devices.  This patch works around the problem not trying to do a global
device reset on these devices.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>