Fix warning

SVN-Revision: 6756

target/linux/adm5120-2.6/files/arch/mips/adm5120/memory.c

@@ -131,5 +131,5 @@ void __init prom_meminit(void)
 unsigned long __init prom_free_prom_memory(void)
 {
 	/* We do not have to prom memory to free */
-        return;
+        return 0;
 }