net: phy: realtek: add dummy PHY driver for RTL8127ATF

net: phy: realtek: add dummy PHY driver for RTL8127ATF

RTL8127ATF supports a SFP+ port for fiber modules (10GBASE-SR/LR/ER/ZR and
DAC). The list of supported modes was provided by Realtek. According to the
r8127 vendor driver also 1G modules are supported, but this needs some more
complexity in the driver, and only 10G mode has been tested so far.
Therefore mainline support will be limited to 10G for now.
The SFP port signals are hidden in the chip IP and driven by firmware.
Therefore mainline SFP support can't be used here.
This PHY driver is used by the RTL8127ATF support in r8169.
RTL8127ATF reports the same PHY ID as the TP version. Therefore use a dummy
PHY ID.  This PHY driver is used by the RTL8127ATF support in r8169.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/e3d55162-210a-4fab-9abf-99c6954eee10@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>