tools/power/x86/intel-speed-select: Do not export get_physical_id

Now, all the get_physical_pkg/die/core_id() users are inside
isst-config.c, so no need to export these APIs.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>