x86 gart: rename CONFIG_IOMMU to CONFIG_GART_IOMMU

This patch renames the IOMMU config option to GART_IOMMU because in fact it
means the GART and not general support for an IOMMU on x86.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Acked-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/pci_64.h b/include/asm-x86/pci_64.h
index 9baa46d..ef54226 100644
--- a/include/asm-x86/pci_64.h
+++ b/include/asm-x86/pci_64.h
@@ -37,7 +37,7 @@
  */
 #define PCI_DMA_BUS_IS_PHYS (dma_ops->is_phys)
 
-#if defined(CONFIG_IOMMU) || defined(CONFIG_CALGARY_IOMMU)
+#if defined(CONFIG_GART_IOMMU) || defined(CONFIG_CALGARY_IOMMU)
 
 #define DECLARE_PCI_UNMAP_ADDR(ADDR_NAME)	\
 	dma_addr_t ADDR_NAME;