x86: intel-iommu: Convert detect_intel_iommu to use iommu_init hook

This changes detect_intel_iommu() to set intel_iommu_init() to
iommu_init hook if detect_intel_iommu() finds the IOMMU.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: chrisw@sous-sol.org
Cc: dwmw2@infradead.org
Cc: joerg.roedel@amd.com
Cc: muli@il.ibm.com
LKML-Reference: <1257849980-22640-6-git-send-email-fujita.tomonori@lab.ntt.co.jp>
[ -v2: build fix for the !CONFIG_DMAR case ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

drivers/pci/dmar.c

@@ -616,6 +616,10 @@ void __init detect_intel_iommu(void)
 		if (ret && !no_iommu && !iommu_detected && !swiotlb &&
 		    !dmar_disabled)
 			iommu_detected = 1;
+#endif
+#ifdef CONFIG_X86
+		if (ret)
+			x86_init.iommu.iommu_init = intel_iommu_init;
 #endif
 	}
 	early_acpi_os_unmap_memory(dmar_tbl, dmar_tbl_size);