selftests: netfilter: remove stray bash debug line

commit 3e6ed770 upstream.

This should not be there.

Fixes: 2de03b45

 ("selftests: netfilter: add flowtable test script")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>