hwmon: (jc42) Consistently use bit and bitfield macros in the driver

Use BIT() and GENMASK() macros for defining the bitfields inside the
registers. Also use FIELD_GET() and FIELD_PREP() where appropriate. This
makes the coding style within the driver consistent. No functional
changes intended.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>