rule: print chain and flowtable devices in quotes

rule: print chain and flowtable devices in quotes

Print devices in quotes, for consistency with:

- the existing chain listing with single device:

  type filter hook ingress device "lo" priority filter; policy accept

- the ifname datatype used in sets.

In general, tokens that are user-defined, not coming in the datatype
symbol list, are enclosed in quotes.

Fixes: 3fdc7541fba0 ("src: add multidevice support for netdev chain")
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>