ACPI: PCI: Drop ACPI_PCI_COMPONENT that is not used any more

After dropping all of the code using ACPI_PCI_COMPONENT drop the
definition of it too and update the documentation to remove all
ACPI_PCI_COMPONENT references from it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>