x86: PAT: move track untrack pfnmap stubs to asm-generic

Impact: Cleanup and branch hints only.

Move the track and untrack pfn stub routines from memory.c to asm-generic.
Also add unlikely to pfnmap related calls in fork and exit path.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 2aa792b..875192bf 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -339,12 +339,10 @@
 
 #define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)
 
-/* Indicate that x86 has its own track and untrack pfn vma functions */
-#define track_pfn_vma_new track_pfn_vma_new
-#define track_pfn_vma_copy track_pfn_vma_copy
-#define untrack_pfn_vma untrack_pfn_vma
-
 #ifndef __ASSEMBLY__
+/* Indicate that x86 has its own track and untrack pfn vma functions */
+#define __HAVE_PFNMAP_TRACKING
+
 #define __HAVE_PHYS_MEM_ACCESS_PROT
 struct file;
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,