ACPI / PCI / PCIe: Rework _OSC handling (v2)

Hi,

This is the second iteration of the patchset based on
https://patchwork.kernel.org/patch/114917/ and the comments I received on that patch. Hopefully, I took all of the comments into account this time.

[1/8] - Introduce acpi_pci_osc_control_query() allowing the caller to get a
mask of _OSC control bits the BIOS allows the kernel to control for a given PCI root bridge.

[2/8] - Introduce pci_aer_available() allowing the caller to check if the
AER service driver should be enabled.

[3/8] - Introduce kernel command line switch pcie_ports=.

[4/8] - Rework the PCIe port driver to request _OSC control for all serives at
once.

[5/8] - Disable PCIe port services (that might be enabled by the BIOS) during
initialization.

[6/8] - Remove the PCIe port driver modules exit function.

[7/8] - Rework acpi_pci_osc_control_set() so that it doesn't use cached
result of a query and remove the fields of struct acpi_pci_root that
aren't used any more.

[8/8] - Reorder checks in acpi_pci_osc_control_set()

Thanks,
Rafael