net: Call ip[6]tables-restore with -w parameter

New ip[6]tables-restore utils has this parameter,
which allows to wait for xtables lock, if it's
occupied. When they don't wait, then the restore
of iptables fails.

Old versions just ignore this parameter
with error in stderr, but it does not make them
fail. So, pass it unconditionally.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>