ixgbe: Add function for setting XPS queue mapping

This change adds support for ixgbe to configure the XPS queue mapping on
load.  The result of this change is that on open we will now be resetting
the number of Tx queues, and then setting the default configuration for XPS
based on if ATR is enabled or disabled.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Reviewed-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>