x86: switch pci-gart over to using set_memory_np() instead of clear_kernel_mapping()

pci-gart needs to unmap the IOMMU aperture to prevent cache corruptions.

Switch this over to using set_memory_np() instead of clear_kernel_mapping().
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/pci-gart_64.c

@@ -731,7 +731,8 @@ void __init gart_iommu_init(void)
 	 * the backing memory. The GART address is only used by PCI
 	 * devices.
 	 */
-	clear_kernel_mapping((unsigned long)__va(iommu_bus_base), iommu_size);
+	set_memory_np((unsigned long)__va(iommu_bus_base),
+				iommu_size >> PAGE_SHIFT);
 
 	/*
 	 * Try to workaround a bug (thanks to BenH)