hwmon: (nct6775) Fix incorrect parenthesization in nct6775_write_fan_div()

Commit 4ef27745 ("hwmon: (nct6775) Convert register access to
regmap API") fumbled the shifting & masking of the fan_div values such
that odd-numbered fan divisors would always be set to zero.  Fix it so
that we actually OR in the bits we meant to.

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Fixes: 4ef27745 ("hwmon: (nct6775) Convert register access to regmap API")
Cc: stable@kernel.org # v5.19+
Link: https://lore.kernel.org/r/20230102212857.5670-1-zev@bewilderbeest.net


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