platform/x86:intel/pmc: Call pmc_get_low_power_modes from platform init

platform/x86:intel/pmc: Call pmc_get_low_power_modes from platform init

In order to setup a table of low power mode requirements for Meteor Lake,
pmc_core_get_low_power_modes() will need to be run from platform init code
so that the enabled modes are known, allowing the use of the
pmc_for_each_mode helper. Make the function global and call it from the
platform init code.

Signed-off-by: Xi Pardee <xi.pardee@intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231129222132.2331261-12-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>