Fix off by one in pfn_valid

From Jim Paradis <jparadis@redhat.com>

When I gave proposed the fix to pfn_valid() for RHEL4, Stephen Tweedie's
sharp eyes caught this:

Index: linux/include/asm-x86_64/mmzone.h
===================================================================
--- linux.orig/include/asm-x86_64/mmzone.h
+++ linux/include/asm-x86_64/mmzone.h
@@ -54,7 +54,7 @@ static inline __attribute__((pure)) int 
 
 #define pfn_valid(pfn) ((pfn) >= num_physpages ? 0 : \
 			({ u8 nid__ = pfn_to_nid(pfn); \
-			   nid__ != 0xff && (pfn) >= node_start_pfn(nid__) && (pfn) <= node_end_pfn(nid__); }))
+			   nid__ != 0xff && (pfn) >= node_start_pfn(nid__) && (pfn) < node_end_pfn(nid__); }))
 #endif
 
 #define local_mapnr(kvaddr) \