net: bridge: mcast: querier and query state affect only current context type

It is a minor optimization and better behaviour to make sure querier and
query sending routines affect only the matching multicast context
depending if vlan snooping is enabled (vlan ctx vs bridge ctx).
It also avoids sending unnecessary extra query packets.

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>