net: dsa: mt7530: get rid of mt753x_mac_config()

There is no need for a separate function to call
priv->info->mac_port_config(). Call it from mt753x_phylink_mac_config()
instead and remove mt753x_mac_config().

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>