platform/x86: intel_pmc_core: Add option to set/clear LPM mode

platform/x86: intel_pmc_core: Add option to set/clear LPM mode

By default the Low Power Mode (LPM or sub-state) status registers will
latch condition status on every entry into Package C10. This is
configurable in the PMC to allow latching on any achievable sub-state. Add
a debugfs file to support this.

Also add the option to clear the status registers to 0. Clearing the status
registers before testing removes ambiguity around when the current values
were set.

The new file, latch_lpm_mode, looks like this:

	[c10] S0i2.0 S0i3.0 S0i2.1 S0i3.1 S0i3.2 clear

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210417031252.3020837-8-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>