x86: GART: Convert gart_iommu_hole_init() to use iommu_init hook

This changes gart_iommu_hole_init() to set gart_iommu_init() to
iommu_init hook if gart_iommu_hole_init() finds the GART IOMMU.

We can kill the code to check if we found the IOMMU in
gart_iommu_init() since gart_iommu_hole_init() sets
gart_iommu_init() only when it found 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: <1257849980-22640-4-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 128111d..03933cf 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -28,6 +28,7 @@
 #include <asm/pci-direct.h>
 #include <asm/dma.h>
 #include <asm/k8.h>
+#include <asm/x86_init.h>
 
 int gart_iommu_aperture;
 int gart_iommu_aperture_disabled __initdata;
@@ -400,6 +401,7 @@
 
 			iommu_detected = 1;
 			gart_iommu_aperture = 1;
+			x86_init.iommu.iommu_init = gart_iommu_init;
 
 			aper_order = (read_pci_config(bus, slot, 3, AMD64_GARTAPERTURECTL) >> 1) & 7;
 			aper_size = (32 * 1024 * 1024) << aper_order;