kvm/openpic: in-kernel mpic support

Enables support for the in-kernel MPIC that thas been merged into the
KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
Graf (along with some other improvements).

Note from Alex regarding kvm_irqchip_create():

  On x86, one would call kvm_irqchip_create() to initialize an
  in-kernel interrupt controller.  That function then goes ahead and
  initializes global capability variables as well as the default irq
  routing table.

  On ppc, we can't call kvm_irqchip_create() because we can have
  different types of interrupt controllers.  So we want to do all the
  things that function would do for us in the in-kernel device init
  handler.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>