Merge branch 'dsa-cpu-flood'

Vladimir Oltean says:

====================
Always flood multicast to the DSA CPU port

Discussing with Qingfang, it became obvious that DSA is not prepared to
disable multicast flooding towards the CPU port under any circumstance
right now, and this in fact breaks traffic quite blatantly.

This series is a revert done in reverse chronological order. These
should be propagated to stable trees up to commit a8b659e7 ("net:
dsa: act as passthrough for bridge port flags") which is in v5.12.
For older kernels, that commit blocks further backporting, so I need to
send a modified version of patch 3 separately to Greg after these go
into "net".

v1->v2: delete unused b53_set_mrouter function prototype
====================

Signed-off-by: David S. Miller <davem@davemloft.net>