ixgbevf: Add support for XDP_TX action

This implements the XDP_TX action which is modeled on the ixgbe
implementation. However instead of using CPU id to determine which XDP
queue to use, this uses the received RX queue index, which is similar
to i40e. Doing this eliminates the restriction that number of CPUs not
exceed number of XDP queues that ixgbe has.

Also, based on the number of queues available, the number of TX queues
may be reduced when an XDP program is loaded in order to accommodate the
XDP queues.

Based largely on
commit 33fdc82f ("ixgbe: add support for XDP_TX action")

Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>