ixgbe: add support for 82599 based X520 10G Dual KX4 Mezz card

This patch adds device support for the 82599 based X520 10GbE
Dual Port KX4 Mezzanine card.

Signed-off-by: Don <Skidmore&lt;donald.c.skidmore@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>