kernel/x86: Initialize IO-APIC only after PCI enumeration is complete.

Before the PCI refactor, PCI initialization/enumeration occurred
immediately after the PCI module was loaded, and so by the time
we got to IOAPIC initialization, it was already complete.

After the refactor, PCI enumeration is deferred until slightly later,
and so we would try to initialize IO-APICs without knowing PCI
information. This would fail, as read_irq_routing_table needs to
have that available.

Hopefully fixes #18425, #18393, #18398.

Change-Id: I1e4b06367da26eeb10085a1c6322ed39885b632b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6476
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

pci/x86: Reimplement PCIe configuration mechanism using ECAM.

This allows us to drop the PCI-specific ACPI management entirely.
Confirmed working on x86, and the fallbacks when there is no ACPI
also still work.

Change-Id: I6dac9f5539f99b934b17b341634ce22628bc66fd
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6470
Reviewed-by: X512 <danger_mail@list.ru>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

bus_managers/pci: split PCI controller to separate add-on

busses/pci/x86: add
Other add-ons are in following commits.

Change-Id: I7a77bfaef0e8995917b4b54c8369d7075533ec26
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6220
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>