Fix !CONFIG_DMAR build failure introduced by Intel IOMMU Pass Through Support

This updated patch should fix the compiling errors and remove the extern
iommu_pass_through from drivers/pci/intel-iommu.c file.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

arch/ia64/kernel/pci-dma.c

@@ -32,6 +32,8 @@ int force_iommu __read_mostly = 1;
 int force_iommu __read_mostly;
 #endif
 
+int iommu_pass_through;
+
 /* Dummy device used for NULL arguments (normally ISA). Better would
    be probably a smaller DMA mask, but this is bug-to-bug compatible
    to i386. */

arch/x86/kernel/pci-dma.c

@@ -32,6 +32,8 @@ int no_iommu __read_mostly;
 /* Set this to 1 if there is a HW IOMMU in the system */
 int iommu_detected __read_mostly = 0;
 
+int iommu_pass_through;
+
 dma_addr_t bad_dma_address __read_mostly = 0;
 EXPORT_SYMBOL(bad_dma_address);
 
@@ -160,8 +162,6 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 	return page_address(page);
 }
 
-extern int iommu_pass_through;
-
 /*
  * See <Documentation/x86_64/boot-options.txt> for the iommu kernel parameter
  * documentation.

drivers/pci/intel-iommu.c

@@ -288,7 +288,6 @@ int dmar_disabled = 1;
 static int __initdata dmar_map_gfx = 1;
 static int dmar_forcedac;
 static int intel_iommu_strict;
-int iommu_pass_through;
 
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
 static DEFINE_SPINLOCK(device_domain_lock);