platform/x86: pmc_core: Use descriptive names for LPM registers

platform/x86: pmc_core: Use descriptive names for LPM registers

TigerLake Lower Power Mode (LPM) registers are grouped by functionality
but were given simple enumerated names in the code (lpm0, lpm1, ...).
Instead, give the register blocks names that describe their usage.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201006224702.12697-2-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>