hwmon: New driver for the National Semiconductor LM73

The National Semiconductor LM73 is a single temperature sensor, much
like the famous LM75.

Signed-off-by: Adrien Demarez <adrien.demarez@bolloretelecom.eu>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

diff --cc MAINTAINERS
Simple merge

diff --cc drivers/hwmon/Kconfig
Simple merge

diff --cc drivers/hwmon/Makefile
Simple merge

diff --cc drivers/hwmon/lm73.c
Simple merge