VT-d: bind IRQs to CPUs local to the node the IOMMU is on

VT-d: bind IRQs to CPUs local to the node the IOMMU is on

This extends create_irq() to take a node parameter, allowing the
resulting IRQ to have its destination set to a CPU on that node right
away, which is more natural than having to post-adjust this (and
get e.g. a new IRQ vector assigned despite a fresh one was just
obtained).

All other callers of create_irq() pass NUMA_NO_NODE for the time being.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>