batman-adv: use batctl for configuration

batman-adv: use batctl for configuration

The batctl binary is currently optional for batman-adv installations. But
new configuration settings will only be exposed via generic netlink. The
batctl tool will therefore be required to modify them.

batctl must therefore no longer depend on batman-adv but batman-adv must
depend on batctl. Some already implemented settings are already moved to
batctl.

Signed-off-by: Sven Eckelmann <sven@narfation.org>