hwmon: (tmp401) use smb word operations instead of 2 smb byte operations

tmp401 separately read/wrote high and low bytes of temperature values while
the hardware supports reading/writing those values in one operation. Driver
has been modified to use word operations where possible.

Tested with a tmp432 sensor on a mips64 platform.

Signed-off-by: Jeroen De Wachter <jeroen.de_wachter.ext@nokia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>