nfp: move queue variable init

nd_q is only used at the very end of nfp_net_tx(), there is no need
to initialize it early.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>