tests: shell: make testcases which using tcp/udp port more rubost

tests: shell: make testcases which using tcp/udp port more rubost

In my mechain, port 12345 is mapped to italk in /etc/services:
  italk           12345/tcp               # Italk Chat System

So when we add nft rule with udp port "12345", nft list ruleset
will displayed it as "italk", that cause the result is not same
with expected, then testcase fail.

Add "-nn" option when dump the rulesets from the kernel, make
testcases which using tcp/udp port more rubost.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Acked-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>