[NET]: Reduce sizeof(struct flowi) by 20 bytes.

As suggested by David, just kill off some unused fields in dnports to
reduce sizef(struct flowi). If they come back, they should be moved to
nl_u.dn_u in order not to enlarge again struct flowi

[ Modified to really delete this stuff instead of using #if 0. -DaveM ]

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>