iommu/vt-d, trivial: clean sparse warnings

Clean up most sparse warnings in Intel DMA and interrupt remapping
drivers.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>

diff --cc drivers/iommu/dmar.c
Simple merge

diff --cc drivers/iommu/intel-iommu.c
Simple merge

diff --cc drivers/iommu/irq_remapping.c
Simple merge