hwmon: (acpi_power_meter) Convert ACPI driver to a platform one

hwmon: (acpi_power_meter) Convert ACPI driver to a platform one

In all cases in which a struct acpi_driver is used for binding a driver
to an ACPI device object, a corresponding platform device is created by
the ACPI core and that device is regarded as a proper representation of
underlying hardware.  Accordingly, a struct platform_driver should be
used by driver code to bind to that device.  There are multiple reasons
why drivers should not bind directly to ACPI device objects [1].

Overall, it is better to bind drivers to platform devices than to their
ACPI companions, so convert the hwmon ACPI power meter driver to a
platform one.

After this change, the subordinate hwmon device will be registered
under the platform device representing the ACPI power meter, sysfs
notifications will trigger on that device, and diagnostic messages
will be printed relative to it instead of its ACPI companion.

Link: https://lore.kernel.org/all/2396510.ElGaqSPkdT@rafael.j.wysocki/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/1952740.tdWV9SEqCh@rafael.j.wysocki
Signed-off-by: Guenter Roeck <linux@roeck-us.net>