hwmon: (sis5595) drop unused DIV_TO_REG function

'DIV_TO_REG' function is not used:

  sis5595.c:159:18: error: unused function 'DIV_TO_REG' [-Werror,-Wunused-function]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240225202841.60740-1-krzysztof.kozlowski@linaro.org


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