net: dsa: b53: fix BCM5325/65 ARL entry multicast port masks

net: dsa: b53: fix BCM5325/65 ARL entry multicast port masks

We currently use the mask 0xf for writing and reading b53_entry::port,
but this is only correct for unicast ARL entries. Multicast ARL entries
use a bitmask, and 0xf is not enough space for ports > 3, which includes
the CPU port.

So extend the mask accordingly to also fit port 4 (bit 4) and MII (bit
5). According to the datasheet the multicast port mask is [60:48],
making it 12 bit wide, but bits 60-55 are reserved anyway, and collide
with the priority field at [60:59], so I am not sure if this is valid.
Therefore leave it at the actual used range, [53:48].

The ARL search result register differs a bit, and there the mask is only
[52:48], so only spanning the user ports. The MII port bit is
contained in the Search Result Extension register. So create a separate
search result parse function that properly handles this.

Fixes: c45655386e53 ("net: dsa: b53: add support for FDB operations on 5325/5365")
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Link: https://patch.msgid.link/20251128080625.27181-6-jonas.gorski@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>