acpi: numa: Add helper function to retrieve the performance attributes

Add helper to retrieve the performance attributes based on the device
handle.  The helper function is exported so the CXL driver can use that
to acquire the performance data between the CPU and the CXL host bridge.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/170319618721.2212653.5552947472849081786.stgit@djiang5-mobl3


Signed-off-by: Dan Williams <dan.j.williams@intel.com>