nfp: remove defines for unused control bits

NFP driver ABI contains bits for L2 switching which were never
implemented in initially envisioned form.

Remove the defines, and open up the possibility of
reclaiming the bits for other uses.

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>