hwmon: (mr75203) update pvt->v_num and vm_num to the actual number of used sensors

This issue is relevant when "intel,vm-map" is set in device-tree, and
defines a lower number of VMs than actually supported.

This change is needed for all places that use pvt->v_num or vm_num
later on in the code.

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/20220908152449.35457-4-farbere@amazon.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>