ixgbe: DCB, implement ieee_setapp dcbnl ops

Implement ieee_setapp dcbnl ops in ixgbe. This is required
to setup FCoE which requires dedicated resources. If the
app data is not for FCoE then no action is taken in ixgbe
except to add it to the dcb_app_list.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>