batman-adv: fix local translation table output

The last-seen field has to be printed for all the local
entries but the one marked with the no-purge flag

Introduced by 15727323d9f8864b2d41930940acc38de987045a
("batman-adv: don't print the last_seen time for bat0 TT local entry")

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>