realtek: dsa: rtl931x: remove enabling MAC from phylink_mac_config

realtek: dsa: rtl931x: remove enabling MAC from phylink_mac_config

Originally, phylink_mac_config first disabled the MAC, then triggered
the SerDes setup and then re-enabled MAC. SerDes setup has been moved to
the PCS driver now but pcs_config is called AFTER phylink_mac_config by
phylink subsystem.

Thus, just disable the MAC in phylink_mac_config. After PCS has setup
the SerDes, the MAC should be properly brought up in a mac_link_up call
coming from the phylink subsystem.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/20369
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>