ARM64 ACPI status report 3 (final)

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Changes since the last update:

 - intrctl(8) is now supported on ARM and ARM64, along with
   intr_establish_xname.
 - Added support for GICv2m MSI/MSI-X on non-ACPI (FDT) platforms.
 - We can now build ARM64 kernels with ACPI and without PCI.
 - Fixed an issue where ARM64 bus_dma would only allocate memory from the
   first memory range.
 - Lots and lots of testing and bug fixes related to MSI/MSI-X on GICv3.
 - Added support to bootaa64.efi for loading kernels over NFS.
 - When netbooting, bootaa64.efi will pass the network interface's MAC
   address to the kernel to help it auto-detect the correct root device.
 - Fixed acpi_intr_establish to use a new MD interface for establishing
   interrupts; the previous interface (acpi_md_OsInstallInterruptHandler)
   is meant for ACPI subsystem interrupts and does not allow the caller to
   pass in IPL, mpsafe hints, etc.
 - Added support for PCI I/O space to acpipchb(4). This is required for
   virtio at pci.

So where we are today:

 - Softiron Overdrive 1000: works, fully supported
 - QEMU (aarch64-softmmu): works, fully supported
 - QEMU (KVM w/ GICv3-ITS): works, tested on ROCKPro64, fully supported
 - Scaleway ARM64 VPS: works, tested on 4 and 6 CPU configurations, fully
   supported
 - Gigabyte MT30-GS2: boots, xhci and sata not working (Nick has the
   hardware and is working on these issues)
 - (not SBSA compliant, but for fun) Raspberry Pi 3: kernel starts, does
   not boot due to lack of driver attach glue for ACPI.

Cheers,
Jared