ixgbe: add device support for 82598AT (copper 10GbE) adapters

Intel is currently shipping support for adapters with a phy
that does 10GBase-T (copper), which is 10 Gigabit ethernet
over standard Category 6 cabling.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>