net: dsa: mv88e6171: Add support for reading the temperature

This chip also has a temperature sensor which can be read using the
common code. In order to use it, add the needed mutex protection for
accessing registers via the shared code.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed