hwmon: (da9052) Fix adc to voltage calculation

The ADC resolution of the PMIC is 10-bits, this means that the maximum
possible value is 1023 and not the 1024 as originally in the code.

Signed-off-by: Anthony Olech <anthony.olech.opensource@diasemi.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>