platform/x86: intel_pmc_core: Show LPM residency in microseconds

platform/x86: intel_pmc_core: Show LPM residency in microseconds

Modify the low power mode (LPM or sub-state) residency counters to display
in microseconds just like the slp_s0_residency counter. The granularity of
the counter is approximately 30.5us per tick. Double this value then divide
by two to maintain accuracy.

Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Rajneesh Bhardwaj <irenic.rajneesh@gmail.com>
Link: https://lore.kernel.org/r/20210417031252.3020837-5-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>