Backport switchdev fix for bridge-in-bridge configurations to linux-5.4

Hi,

Is it possible to backport the commit "net: switchdev: do not propagate bridge updates across bridges" [1] to linux-5.4?

This patch fixes faulty hardware configuration when nesting DSA-offloaded bridges into software bridges, which can cause vlan_filtering to be disabled in hardware, even though it should be enabled. Therefore, ports/vlans get connected, even though they should be isolated.

A backport of this patch for linux-5.4 has recently been accepted in OpenWrt [2]

Best regards, Fabian Bläse

[1] 07c6f9805f12f1bb538ef165a092b300350384aa [2] https://github.com/openwrt/openwrt/pull/4493