net: bridge: multicast: notify switchdev driver whenever MC processing gets disabled

mainline inclusion
from mainline-v5.17-rc5
commit c832962a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7V613

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c832962ac972082b3a1f89775c9d4274c8cb5670



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Whenever bridge driver hits the max capacity of MDBs, it disables
the MC processing (by setting corresponding bridge option), but never
notifies switchdev about such change (the notifiers are called only upon
explicit setting of this option, through the registered netlink interface).

This could lead to situation when Software MDB processing gets disabled,
but this event never gets offloaded to the underlying Hardware.

Fix this by adding a notify message in such case.

Fixes: 147c1e9b ("switchdev: bridge: Offload multicast disabled")
Signed-off-by: Oleksandr Mazur <oleksandr.mazur@plvision.eu>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://lore.kernel.org/r/20220215165303.31908-1-oleksandr.mazur@plvision.eu


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Conflicts:
	net/bridge/br_multicast.c

Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>