Functions alloc_iommu() and parse_ioapics_under_ir()
are only used internally, so mark them as static.

[Joerg: Made detect_intel_iommu() non-static again for IA64]
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: NJoerg Roedel <joro@8bytes.org>