m68k: Export empty_zero_page for ZERO_PAGE usage in modules.

ext4 uses ZERO_PAGE(0) to zero out blocks.  We need to export
different symbols in different arches for the usage of ZERO_PAGE
in modules.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

arch/m68k/mm/init.c

@@ -69,6 +69,7 @@ void __init m68k_setup_node(int node)
  */
 
 void *empty_zero_page;
+EXPORT_SYMBOL(empty_zero_page);
 
 void show_mem(void)
 {