generic: net: phy: realtek: work-around hang on SerDes setup

generic: net: phy: realtek: work-around hang on SerDes setup

On some but not all devices using the RTL8221B 2.5GBit/s PHY the SerDes
setup sequence may hang under some circumstances (eg. <2500M link
partner present during boot).

RTL8221B-VB-CG 2.5Gbps PHY (C45) mdio-bus:01: rtl822xb_config_init failed: -110

Work-around the issue by performing a hardware reset and subsequent
retry of the SerDes setup, which seems to always succeed.

Doing this requires moving ALDPS setup to config_init (which is anyway
the better place for that) as it otherwise doesn't survive the reset.

Also disable listening on MDIO address 0 which may be used by other PHYs
despite being spec'ed as "broadcast address", as bus activity on address
0 may otherwise confuse the RealTek PHY for good reasons.

Tested-by: Luis Mita <luis@luismita.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit c87a767801ef375feadb0a5c41d5a674ad3a7d2c)
Link: https://github.com/openwrt/openwrt/pull/17790
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>