ixgbe: Fix handling of macvlan Tx offload

This update makes it so that we report the actual number of Tx queues via
real_num_tx_queues but are still restricted to RSS on only the first pool
by setting num_tc equal to 1. Doing this locks us into only having the
ability to setup XPS on the queues in that pool, and only those queues
should be used for transmitting anything other than macvlan traffic.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>