ia64: Get rid of iommu_pass_through

This variable has no users anymore so it can be removed.

Signed-off-by: Joerg Roedel <jroedel@suse.de>

arch/ia64/include/asm/iommu.h

@@ -8,10 +8,8 @@
 extern void no_iommu_init(void);
 #ifdef	CONFIG_INTEL_IOMMU
 extern int force_iommu, no_iommu;
-extern int iommu_pass_through;
 extern int iommu_detected;
 #else
-#define iommu_pass_through	(0)
 #define no_iommu		(1)
 #define iommu_detected		(0)
 #endif