T480S Heads firmware lack ACPI P-state tables.

Without commit 91173, T480S systems running Heads firmware lack ACPI P-state tables. This primarily affects: Xen hypervisor frequency scaling (the original reported issue) Operating systems that rely on ACPI _PSS/_PCT/_PPC tables for CPU power management outlined here: https://ticket.coreboot.org/issues/623 Fix availble: https://review.coreboot.org/c/coreboot/+/91173