bhyve: Support legacy PCI interrupts on arm64

This allows us to remove various #ifdef hacks and enable building more
PCI devices.

Note that a hole is left in the interrupt mapping for the RTC rather
than having the two core devices straddle the PCIe interrupts. QEMU's
virt machine also takes this approach.

Reviewed by: jhb
MFC after: 2 weeks
Obtained from: CheriBSD

Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

Add SPDX tags to bhyve(8).

Discussed with: rgrimes, pfg and mav.
Obtained from: TrueOS
MFC after: 4 weeks.
Sponsored by: iXsystems Inc.

Make PCI interupts allocation static when using bootrom (UEFI).

This makes factual interrupt routing match one shipped with UEFI firmware.
With old firmware this make legacy interrupts work reliable for functions 0
of PCI slots 3-6. Updated UEFI image fixes problem completely.

Reassign copyright statements on several files from Advanced
Computing Technologies LLC to Hudson River Trading LLC.

Approved by: Hudson River Trading LLC (who owns ACT LLC)
MFC after: 1 week

Implement a PCI interrupt router to route PCI legacy INTx interrupts to
the legacy 8259A PICs.
- Implement an ICH-comptabile PCI interrupt router on the lpc device with
8 steerable pins configured via config space access to byte-wide
registers at 0x60-63 and 0x68-6b.
- For each configured PCI INTx interrupt, route it to both an I/O APIC
pin and a PCI interrupt router pin. When a PCI INTx interrupt is
asserted, ensure that both pins are asserted.
- Provide an initial routing of PCI interrupt router (PIRQ) pins to
8259A pins (ISA IRQs) and initialize the interrupt line config register
for the corresponding PCI function with the ISA IRQ as this matches
existing hardware.
- Add a global _PIC method for OSPM to select the desired interrupt routing
configuration.
- Update the _PRT methods for PCI bridges to provide both APIC and legacy
PRT tables and return the appropriate table based on the configured
routing configuration. Note that if the lpc device is not configured, no
routing information is provided.
- When the lpc device is enabled, provide ACPI PCI link devices corresponding
to each PIRQ pin.
- Add a VMM ioctl to adjust the trigger mode (edge vs level) for 8259A
pins via the ELCR.
- Mark the power management SCI as level triggered.
- Don't hardcode the number of elements in Packages in the source for
the DSDT. iasl(8) will fill in the actual number of elements, and
this makes it simpler to generate a Package with a variable number of
elements.

Reviewed by: tycho