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: Minchan Kim <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: Tejun Heo <[e-mail]>

Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

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

···
 	 * 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;