platform/x86/intel/pmc: Add PSON residency counter

platform/x86/intel/pmc: Add PSON residency counter

Tiger Lake platform onwards, devices have the capability to track the
duration of time that their Power Supply Units (PSUs) are turned off
during S0ix. This patch adds a debugfs file `pson_residency_usec` to
provide access to this counter.

Signed-off-by: Michael Bottini <michael.a.bottini@linux.intel.com>
Signed-off-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20231219042216.2592029-2-rajvi.jingar@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>