bhyve: Add PCI mappings for arm64

• The extended config space and BAR ranges are listed in the FDT.
• Avoid referencing I/O ports in ACPI tables. Currently the arm64 port does not support ACPI in any case.

Reviewed by: corvink, jhb
MFC after: 2 weeks
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D41739