MFC of the ixgbe driver including the follow revisions:

235547,235964,241616,241646,241856,241885,242403,
242421,243714,243716,243718,243721,243724,243725,
243728,243729,243733,243735,243736,243741,243833,
244514,246128,246482,247035,247056,247822,247823

Note: 246482 includes only the changes in the ixgbe driver
      and the buf_ring supporting code in if_var.h and buf_ring.h
      igb and em will be seperate commits, and non-Intel drivers
      can commit the changes at will.

Reviewed by:rss, jhb