nommu: Fix up vmalloc_node() symbol export regression.

Commit e1ca7788 ("mm: add vzalloc() and vzalloc_node() helpers") ended up
accidentally deleting the vmalloc_node() symbol export, resulting in:

"vmalloc_node" [net/core/pktgen.ko] undefined!
"vmalloc_node" [net/netfilter/x_tables.ko] undefined!

regressions.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

mm/nommu.c

@@ -328,6 +328,7 @@ void *vmalloc_node(unsigned long size, int node)
 {
 	return vmalloc(size);
 }
+EXPORT_SYMBOL(vmalloc_node);
 
 /**
  * vzalloc_node - allocate memory on a specific node with zero fill