Fix build failure when MEMORY_HOTPLUG_SPARSE and !HUGETLBFS:

drivers/base/node.c:484: error: implicit declaration of function 'init_node_hugetlb_work'
drivers/base/node.c:582: error: 'node_memory_callback' undeclared (first use in this function)
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/base/node.c

@@ -445,8 +445,12 @@ static int node_memory_callback(struct notifier_block *self,
 }
 #endif	/* CONFIG_HUGETLBFS */
 #else	/* !CONFIG_MEMORY_HOTPLUG_SPARSE */
+
 static int link_mem_sections(int nid) { return 0; }
+#endif	/* CONFIG_MEMORY_HOTPLUG_SPARSE */
 
+#if !defined(CONFIG_MEMORY_HOTPLUG_SPARSE) || \
+    !defined(CONFIG_HUGETLBFS)
 static inline int node_memory_callback(struct notifier_block *self,
 				unsigned long action, void *arg)
 {
@@ -455,7 +459,7 @@ static inline int node_memory_callback(struct notifier_block *self,
 
 static void init_node_hugetlb_work(int nid) { }
 
-#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+#endif
 
 int register_one_node(int nid)
 {