acpica, pci_host_generic_acpi: redo pci_host_generic_acpi.c

This is a major update for pci_host_generic_acpi.c, the current
implementation has some gaps that are better fixed up in one go.
The changes are to:

• Follow x86 method of not adding PCI resources to PCI host bridge in ACPI code. This has been moved to pci_host_generic_acpi.c, where we walk thru its resources of the host bridge and add them.
• Fixup code in pci_host_generic_acpi.c to read all decoded ranges and update the 'ranges' property. This allows us to share most of the code with generic implementation (and the FDT one).
• Parse and setup IO ranges and bus ranges when walking the resources above. Drop most of the changes related to this from acpica code.
• Add the ECAM memory area as mem resource 0. Implement the logic to get the ECAM area from MCFG (using bus range which we now decode), or from _CBA (using _BBN/bus range). Drop aarch64 ifdefs from acpica code which did part of this.
• Switch resource activation to similar code as FDT implementation, this can be moved into generic implementation in a later pass.
• Drop the mechanism of using the 7th bit of bus number as the domain, this is not correct and will work only in very specific cases. Use _SEG as PCI domain and use the bus ranges of the host bridge to provide start bus number.

This commit should not make any functional change to dev/acpica/acpi.c
for other architectures, almost all the changes there are to revert
earlier additions in this file done for aarch64.

Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D17791