net: dsa: lantiq_gswip: Update comments in gswip_port_vlan_filtering()

Update the comments in gswip_port_vlan_filtering() so it's clear that
there are two separate cases, one for "tag based VLAN" and another one
for "port based VLAN".

Suggested-by: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Martin Schiller <ms@dev.tdt.de>
Link: https://lore.kernel.org/r/20240611135434.3180973-12-ms@dev.tdt.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>