kselftests: netfilter: fix leftover net/net-next merge conflict

In nf-next, I had extended this script to also cover NAT support for the
inet family.

In nf, I extended it to cover a regression with 'fully-random' masquerade.

Make this script work again by resolving the conflicts as needed.

Fixes: 8b448365

 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>