net: phy: dp83td510: add SQI support

Convert MSE (mean-square error) values to SNR and split it SQI (Signal Quality
Indicator) ranges. The used ranges are taken from "OPEN ALLIANCE - Advanced
diagnostic features for 100BASE-T1 automotive Ethernet PHYs"
specification.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220620115601.2035452-1-o.rempel@pengutronix.de


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