platform/x86/intel/tpmi: Add debugfs interface

Add debugfs interface for debugging TPMI configuration and register
contents. This shows PFS (PM Feature structure) for each TPMI device.

For each feature, show full register contents and allow to modify
register at an offset.

This debugfs interface is not present on locked down kernel with no
DEVMEM access and without CAP_SYS_RAWIO permission.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230712225950.171326-3-srinivas.pandruvada@linux.intel.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>