net: phy: realtek: add hwmon support for temp sensor on RTL822x

This adds hwmon support for the temperature sensor on RTL822x.
It's available on the standalone versions of the PHY's, and on
the integrated PHY's in RTL8125B/RTL8125D/RTL8126.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/ad6bfe9f-6375-4a00-84b4-bfb38a21bd71@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>