mips: zero out pg_data_t when it's allocated

This patch is preparation for the next patch which removes the zeroing of
the pg_data_t in core MM.  All archs except MIPS already do this.
Signed-off-by: NMinchan Kim <minchan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/mips/sgi-ip27/ip27-memory.c

@@ -401,6 +401,7 @@ static void __init node_mem_init(cnodeid_t node)
 	 * Allocate the node data structures on the node first.
 	 */
 	__node_data[node] = __va(slot_freepfn << PAGE_SHIFT);
+	memset(__node_data[node], 0, PAGE_SIZE);
 
 	NODE_DATA(node)->bdata = &bootmem_node_data[node];
 	NODE_DATA(node)->node_start_pfn = start_pfn;