platform/x86/intel/pmc: Add support for variable DMU offsets

platform/x86/intel/pmc: Add support for variable DMU offsets

Add support for handling different DMU Die C6 offsets across platforms.
The previous implementation assumed a uniform DMU Die C6 offset for all
platforms, which is no longer valid after an upcoming change.

Signed-off-by: Xi Pardee <xi.pardee@linux.intel.com>
Link: https://patch.msgid.link/20260505043342.2573556-6-xi.pardee@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>