net: airoha: Rename airoha_set_gdm_port_fwd_cfg() in airoha_set_vip_for_gdm_port()

Rename airoha_set_gdm_port() in airoha_set_vip_for_gdm_port().
Get rid of airoha_set_gdm_ports routine.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>