net: bridge: mcast: handle host state

Since host joins are considered as EXCLUDE {} joins we need to reflect
that in all of *,G ports' S,G entries. Since the S,Gs can have
host_joined == true only set automatically we can safely set it to false
when removing all automatically added entries upon S,G delete.

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