platform/x86: intel_pmc_ipc: Switch to use driver->dev_groups

The driver core provides support for adding additional attributes for
devices via new ->dev_groups member of struct device_driver. Convert the
driver to use that instead of adding the attributes manually.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>