platform/x86/intel: pmc/core: Add Alder Lake low power mode support for pmc core

Alder Lake has 14 status registers that are memory mapped. These
registers show the status of the low power mode requirements. The
registers are latched on every C10 entry or exit and on every s0ix.y
entry/exit. Accessing these registers is useful for debugging any low
power related activities.

Thus, add debugfs entry to access low power mode status registers.

Cc: Chao Qin <chao.qin@intel.com>
Cc: Srinivas Pandruvada <srinivas.pandruvada@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David Box <david.e.box@intel.com>
Tested-by: You-Sheng Yang <vicamo.yang@canonical.com>
Acked-by: Rajneesh Bhardwaj <irenic.rajneesh@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Link: https://lore.kernel.org/r/d27ec98589a5aaa569bbce0e937ed03779fc0a22.1629091915.git.gayatri.kammela@intel.com


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