This is an ia64 portion of IRQ resource deallocation. It implements
pcibios_disable_device() and acpi_unregister_gsi() for ia64.

    o acpi_unregister_gsi()

        Summary of changes for implementing this interface:

        - Add new function iosapic_unregister_intr() into
          arch/ia64/kernel/iosapic.c. This function frees an interrupt
          vector and related data structures.

        - Add new function free_irq_vector() into
          arch/ia64/kernel/irq_ia64.c. This frees an unused vector.

        - Change assign_irq_vector() to be able to support
          free_irq_vector().

    o pcibios_disable_device()

        This calls acpi_pci_irq_disable() to deallocate IRQ resources.
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>