x86_64: move iommu declaration from proto to iommu.h

[akpm@linux-foundation.org: build fix]
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/x86_64/kernel/pci-gart.c b/arch/x86_64/kernel/pci-gart.c
index 12acafd..4918c57 100644
--- a/arch/x86_64/kernel/pci-gart.c
+++ b/arch/x86_64/kernel/pci-gart.c
@@ -28,6 +28,7 @@
 #include <asm/mtrr.h>
 #include <asm/pgtable.h>
 #include <asm/proto.h>
+#include <asm/iommu.h>
 #include <asm/cacheflush.h>
 #include <asm/swiotlb.h>
 #include <asm/dma.h>