iommu, x86: Save the mode (posted or remapped) of an IRTE

Add a new field to struct irq_2_iommu, which captures whether the
associated IRTE is in posted mode or remapped mode. We update this
field when the IRTE is written into the table.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Feng Wu <feng.wu@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <joro@8bytes.org>
Cc: jiang.liu@linux.intel.com
Cc: iommu@lists.linux-foundation.org
Cc: dwmw2@infradead.org
Link: http://lkml.kernel.org/r/1433827237-3382-6-git-send-email-feng.wu@intel.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>