hwmon: make abituguru3_read_increment_offset() static

abituguru3_read_increment_offset() can become static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>