vici: Prevent uninitialized memory access when finding VICI_END in message

VICI_END (7) shouldn't be encoded in a message.  However, if we encounter
it, we should at least set `out` accordingly so callers can abort the
enumeration.  By not doing so previously and returning TRUE, callers
might access the possibly uninitialized name/value arguments passed to
the enumerator.

src/libcharon/plugins/vici/vici_message.c

@@ -189,7 +189,7 @@ METHOD(enumerator_t, parse_enumerate, bool,
 			this->list = FALSE;
 			break;
 		case VICI_END:
-			return TRUE;
+			break;
 		default:
 			DBG1(DBG_ENC, "unknown encoding type: %u", type);
 			return FALSE;