hwmon: (tps23861) Constify struct regmap_config

`tps23861_regmap_config` is not modified and can be declared as const to
move its data to a read-only section.

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240702-hwmon-const-regmap-v1-3-63f6d4765fe0@gmail.com


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