ixgbe: Populate the prio_tc_map in ixgbe_setup_tc

There were cases where the prio_tc_map was not populated when we were
calling open.  This will result in us incorrectly configuring the traffic
classes when DCB is enabled.  In order to correct this I have updated the
code so that we now populate the values prior to allocating the q_vectors
and calling ixgbe_open.

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