kernel: add a bridge feature for filtering BPDU packets on ports

[Andre Heider]

Hi Felix,

I think there's a problem with
a4b5bc20 "kernel: add a bridge feature for filtering BPDU packets on ports"

My lantiq/xrx200 router has 2 radios with 2 wireless networks each:
* nac
   * mesh point
   * master
* bgn
   * master
   * master (guests, isolated)

The first three are bridged with the lan ports.

Before the patch in question clients connected to the bgn master can 
reach clients connected to the nac master (like a simple ping). With the 
patch that doesn't work anymore. Only clients connected to the nac 
master can reach other clients (but weirdly that doesn't seem to apply 
to all clients, only some).

Toggling the isolated option on the guest master doesn't make a 
difference (as it seems to have a similar effect).

With these 3 reverted (on top of da5bb885 "toolchain/gcc: switch to 
version 11 by default") it works again:
Revert "hostapd: let netifd set bridge port attributes for snooping"
Revert "netifd: update to the latest version"
Revert "kernel: add a bridge feature for filtering BPDU packets on ports"

With just the first 2 reverts it's still broken.

Any idea?

Cheers,
Andre