net: micrel: Cable Diagnostics feature for lan8841 PHY

Add support for cable diagnostics in lan8841 PHY. It has the same
registers layout as lan8814 PHY, therefore reuse the functionality.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230208114406.1666671-1-horatiu.vultur@microchip.com


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