arch/x86/mm/numa.c: initialize numa_kernel_nodes in numa_clear_kernel_node_hotplug()

On-stack variable numa_kernel_nodes in numa_clear_kernel_node_hotplug()
was not initialized.  So we need to initialize it.

[akpm@linux-foundation.org: use NODE_MASK_NONE, per David]
Signed-off-by: NTang Chen <tangchen@cn.fujitsu.com>
Tested-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Reported-by: NDave Jones <davej@redhat.com>
Reported-by: NDavid Rientjes <rientjes@google.com>
Tested-by: NDave Jones <davej@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/numa.c

@@ -565,7 +565,7 @@ static void __init numa_init_array(void)
 static void __init numa_clear_kernel_node_hotplug(void)
 {
 	int i, nid;
-	nodemask_t numa_kernel_nodes;
+	nodemask_t numa_kernel_nodes = NODE_MASK_NONE;
 	unsigned long start, end;
 	struct memblock_type *type = &memblock.reserved;