Add support for certain Intel X550 devices.
These include standalone X550 adapters, X552 10GbE backplane, and
X552/X557-AT 10GBASE-T; with the latter two being integrated into Xeon D SoCs.
As well, this bumps the ixgbe version number to 2.8.3, and includes updates
to shared code for support for the new devices.
Differential Revision: D2414
Reviewed by: gnn, adrian
Approved by: jfv (mentor), gnn (mentor)