hwmon: (lm75) Fixup tmp75b clr_mask

The configuration register of the tmp75b sensor is 16bit long, however
the first byte is reserved, so there is not no need to take care of it.

Because the order of the bytes is little endian and it is only necessary
to write one byte, the desired bits must be shifted into a 8 bit range.

Fixes: 39abe9d8

 ("hwmon: (lm75) Add support for TMP75B")
Cc: stable@vger.kernel.org
Signed-off-by: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
Link: https://lore.kernel.org/r/20190801075324.4638-1-iker.perez@codethink.co.uk
Signed-off-by: Guenter Roeck <linux@roeck-us.net>