Expose boot performance metrics via ACPI FPDT

[xen0n]

The table is used by boot performance profiling tools such as systemd-analyze:

https://github.com/systemd/systemd/blob/v259/src/shared/boot-timestamps.c#L21-L26

https://github.com/systemd/systemd/blob/v259/src/shared/acpi-fpdt.c#L108

I believe this should be useful long-term when LoongArch system integrators eventually need to optimize their boot-time performance.

[xry111]

OVMF now supports it: tianocore/edk2#12378

The support for real hardware is under discussion.