hwmon: (tmp401) Use regmap

Use regmap for register accesses to be able to utilize its caching
functionality. This also lets us hide register access differences
in regmap code.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -1951,6 +1951,7 @@ config SENSORS_TMP108
 config SENSORS_TMP401
 	tristate "Texas Instruments TMP401 and compatibles"
 	depends on I2C
+	select REGMAP
 	help
 	  If you say yes here you get support for Texas Instruments TMP401,
 	  TMP411, TMP431, TMP432, and TMP435 temperature sensor chips.