Add fall through comment to source in cpu/

I edited opcodes/mep-asm.c in 1a0670f3 without noticing it was a
generated file.

	* mep.opc (expand_string): Add fall through comment.

cpu/mep.opc

@@ -790,6 +790,7 @@ expand_string (const char *in, int first_only)
 		  break;
 		case '(':
 		  depth++;
+		  /* Fall through.  */
 		default:
 		  args[narg].len++;
 		  break;