hwmon: (mr75203) enable polling for all VM channels

Configure ip-polling register to enable polling for all voltage monitor
channels.
This enables reading the voltage values for all inputs other than just
input 0.

Fixes: 9d823351

 ("hwmon: Add hardware monitoring driver for Moortec MR75203 PVT controller")
Signed-off-by: Eliav Farber <farbere@amazon.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220908152449.35457-7-farbere@amazon.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>