ctrl_type_vals: fix range check

In ctrl_cmd_parse(), fix missing check for not parseable ctrl type.

Fixup for Icd4e96dd9f00876cb70b43cfcf42ab4f10311b28.

Change-Id: I7f8055225e3ee04b2a723bae07b12c42618963a0
diff --git a/src/ctrl/control_cmd.c b/src/ctrl/control_cmd.c
index 1cc8247..cdec8ef 100644
--- a/src/ctrl/control_cmd.c
+++ b/src/ctrl/control_cmd.c
@@ -289,7 +289,7 @@
 	}
 
 	cmd->type = get_string_value(ctrl_type_vals, tmp);
-	if (cmd->type == CTRL_TYPE_UNKNOWN) {
+	if (cmd->type < 0 || cmd->type == CTRL_TYPE_UNKNOWN) {
 		cmd->type = CTRL_TYPE_ERROR;
 		cmd->id = "err";
 		cmd->reply = "Request type unknown";