net: bridge: mcast: fix br_multicast_ctx_vlan_global_disabled helper

net: bridge: mcast: fix br_multicast_ctx_vlan_global_disabled helper

We need to first check if the context is a vlan one, then we need to
check the global bridge multicast vlan snooping flag, and finally the
vlan's multicast flag, otherwise we will unnecessarily enable vlan mcast
processing (e.g. querier timers).

Fixes: a6dc6325c1b7 ("net: bridge: multicast: add vlan state initialization and control")
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://lore.kernel.org/r/20211228153142.536969-1-nikolay@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>