This adds LED support for RTL8125/RTL8126.

Note: Due to missing datasheets changing the 5Gbps link mode isn't
supported for RTL8126.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/f982602c-9de3-4ca6-85a3-2c1d118dcb15@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>