hwmon: (lm75) Convert to use regmap

Convert to use regmap. Leave caching to regmap and drop the register
update function. While this can result in additional read operations
if the temperature register is read continuously, it avoids re-reading
the limit registers and thus overall reduces complexity.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -958,6 +958,7 @@ config SENSORS_LM75
 	tristate "National Semiconductor LM75 and compatibles"
 	depends on I2C
 	depends on THERMAL || !THERMAL_OF
+	select REGMAP_I2C
 	help
 	  If you say yes here you get support for one common type of
 	  temperature sensor chip, with models including: