[PATCH] Fix one last ia64 build problem in Intel IOMMU Pass Through Support

["Luck, Tony" <tony.luck@intel.com>]

On ia64 with CONFIG_DMAR=n and CONFIG_SWIOTLB=y (as used in
arch/ia64/configs/tiger_defconfig) there is still a link
error with iommu_pass_through listed as an undefined symbol:

arch/ia64/kernel/built-in.o: In function `pci_swiotlb_init':
(.init.text+0x7f70): undefined reference to `iommu_pass_through'

Fix it by #defining iommu_pass_through away in asm/iommu.h

Signed-off-by: Tony Luck <tony.luck@intel.com>

---

This fix for the iommu tree/branch that feeds to linux-next

diff --git a/arch/ia64/include/asm/iommu.h b/arch/ia64/include/asm/iommu.h
index 37d41ca..745e095 100644
--- a/arch/ia64/include/asm/iommu.h
+++ b/arch/ia64/include/asm/iommu.h
@@ -9,7 +9,11 @@ extern void pci_iommu_shutdown(void);
 extern void no_iommu_init(void);
 extern int force_iommu, no_iommu;
 extern int iommu_detected;
+#ifdef	CONFIG_DMAR
 extern int iommu_pass_through;
+#else
+#define iommu_pass_through	(0)
+#endif
 extern void iommu_dma_init(void);
 extern void machvec_init(const char *name);