net: dsa: lantiq_gswip: do also enable or disable cpu port

Before commit 74be4bab ("net: dsa: do not enable or disable non user
ports"), gswip_port_enable/disable() were also executed for the cpu port
in gswip_setup() which disabled the cpu port during initialization.

Let's restore this by removing the dsa_is_user_port checks. Also, let's
clean up the gswip_port_enable() function so that we only have to check
for the cpu port once. The operation reordering done here is safe.

Signed-off-by: Martin Schiller <ms@dev.tdt.de>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20240611135434.3180973-7-ms@dev.tdt.de


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