net: dsa: mt7530: fix handling of 802.1X PAE frames

802.1X PAE frames are link-local frames, therefore they must be trapped to
the CPU port. Currently, the MT753X switches treat 802.1X PAE frames as
regular multicast frames, therefore flooding them to user ports. To fix
this, set 802.1X PAE frames to be trapped to the CPU port(s).

Fixes: b8f126a8 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>