Users may have defined additional mesh interfaces. Properly migrate these
to avoid subtly breaking the network config (and make them ready for new
mesh protocols).
Just like we enabled multicast snooping on the batman-adv client bridge
again, let's do the same for the WAN side.
With one exception: The IGMP/MLD querier is kept disabled to avoid
becoming too "bossy"/"noisy" on a foreign network. The main router on
the WAN side should perform querying and by that enable
IGMP/MLD/snooping if it considers this appropriate there.
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
