intel-iommu: move iommu_prepare_gfx_mapping() out of dma_remapping.h

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index f23a020..c1c59a6 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -1686,6 +1686,11 @@
 			printk(KERN_ERR "IOMMU: mapping reserved region failed\n");
 	}
 }
+#else /* !CONFIG_DMAR_GFX_WA */
+static inline void iommu_prepare_gfx_mapping(void)
+{
+	return;
+}
 #endif
 
 #ifdef CONFIG_DMAR_FLOPPY_WA