net: dsa: lantiq_gswip: clarify GSWIP 2.2 VLAN mode in comment

net: dsa: lantiq_gswip: clarify GSWIP 2.2 VLAN mode in comment

The comment above writing the default PVID incorrectly states that
"GSWIP 2.2 (GRX300) and later program here the VID directly."
The truth is that even GSWIP 2.2 and newer maintain the behavior of
GSWIP 2.1 unless the VLANMD bit in PCE Global Control Register 1 is
set ("GSWIP2.2 VLAN Mode").
Fix the misleading comment accordingly.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Acked-by; Hauke Mehrtens <hauke@hauke-m.de>:
Acked-by; Hauke Mehrtens <hauke@hauke-m.de>:
Link: https://patch.msgid.link/018056a575503d9797f3222f71a988e825316be0.1761045000.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>