platform/x86/intel/pmc: Remove unnecessary declarations in header

Remove unnecessary declarations in header file. Variable that are
used by only one .c file are removed from header file and changed
to be static in their corresponding .c file.

Signed-off-by: Xi Pardee <xi.pardee@linux.intel.com>
Link: https://lore.kernel.org/r/20250214214416.10150-3-xi.pardee@linux.intel.com


Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>