net: phy: nxp-tja11xx: log critical health state

TJA1102 provides interrupt notification for the critical health states
like overtemperature and undervoltage.

The overtemperature bit is set if package temperature is beyond 155C°.
This functionality was tested by heating the package up to 200C°

The undervoltage bit is set if supply voltage drops beyond some critical
threshold. Currently not tested.

In a typical use case, both of this events should be logged and stored
(or send to some remote system) for further investigations.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>