intel_iommu: disallow kernel-irqchip=on with IR

When user specify "intremap=on" with "-M kernel-irqchip=on", throw error
and then quit.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>