Merge branch 'bridge-mcast-fix-a-possible-use-after-free-when-removing-a-bridge-port'

Ido Schimmel says:

====================
bridge: mcast: Fix a possible use-after-free when removing a bridge port

Patch #1 fixes a possible use-after-free when removing a bridge port.

Patch #2 adds a test case that triggers the problem.

In net-next we can:

1. Add DEBUG_NET_WARN_ON_ONCE() when a port multicast context is
de-initialized while enabled.

2. When de-initializing a port multicast context, synchronously shutdown
all the timers that were initialized when the context was initialized.
====================

Link: https://patch.msgid.link/20260517121122.188333-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>