From: "Nguyen, Tom L" <tom.l.nguyen@intel.com>

Adds MSI support for ia64.

- Modified existing code in drivers/pci/msi.c and drivers/pci/msi.h to
  include MSI support on IA64 platform.

- Based on the comments received from Zwane Mwaikambo and David Mosberger,
  this patch consolidates the vector allocators as
  assign_irq_vector(AUTO_ASSIGN) has the same semantics as
  ia64_alloc_vector() by converting the existing uses of ia64_alloc_vector()
  to assign_irq_vector(AUTO_ASSIGN).

- Based on the comments received from Zwane Mwaikambo, this patch
  consolidates the semantics of vector allocator assign_irq_vector() in
  drivers/pci/msi.c into the relevant architecture's vector allocator
  assign_irq_vector() in arch/i386/kernel/io_apic.c.

- Regarding vector allocation, this patch modifies the existing function
  assign_irq_vector() to maximize the number of allocated vectors to 188
  before going -ENOSPC.

- Based on your comments, this patch creates <asm-i386/msi.h>,
  <asm-ia64/msi.h> and <asm-x86_64/msi.h>, includes <asm/msi.h> from within
  drivers/pci/msi.h and then places all the code which is currently under
  ifdef in msi.h into the relevant architecture's <asm/msi.h> file.

- Based on your comments, this patch places pci_vector_resources() in
  existing drivers/pci/msi.c in the relevant architecture implementations
  such as into arch/.../pci/irq.c.