platform/x86: intel_pmc_core: Add requirements file to debugfs

platform/x86: intel_pmc_core: Add requirements file to debugfs

Add the debugfs file, substate_requirements, to view the low power mode
(LPM) requirements for each enabled mode alongside the last latched status
of the condition.

After this patch, the new file will look like this:

                    Element |    S0i2.0 |    S0i3.0 |    S0i2.1 |    S0i3.1 |    S0i3.2 |    Status |
            USB2PLL_OFF_STS |  Required |  Required |  Required |  Required |  Required |           |
PCIe/USB3.1_Gen2PLL_OFF_STS |  Required |  Required |  Required |  Required |  Required |           |
       PCIe_Gen3PLL_OFF_STS |  Required |  Required |  Required |  Required |  Required |       Yes |
            OPIOPLL_OFF_STS |  Required |  Required |  Required |  Required |  Required |       Yes |
              OCPLL_OFF_STS |  Required |  Required |  Required |  Required |  Required |       Yes |
            MainPLL_OFF_STS |           |  Required |           |  Required |  Required |           |

Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Co-developed-by: David E. Box <david.e.box@linux.intel.com>
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/20210417031252.3020837-7-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>