platform/x86/amd: pmc: Add helper function to check the cpu id

platform/x86/amd: pmc: Add helper function to check the cpu id

Add a helper routine to check the underlying cpu id, that can be used
across the PMC driver to remove the duplicate code.

Co-developed-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Sanket Goswami <Sanket.Goswami@amd.com>
Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230525141929.866385-4-Shyam-sundar.S-k@amd.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>