pxe: add support for ontimeout token

ontimeout is similar to default, but is the selection on menu timeout.
This is how cobbler sets a default. The label default is supposed to be
the default selection when <enter> is pressed. If both default and
ontimeout are set, last one parsed wins.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c
index acc6a9b..7781469 100644
--- a/common/cmd_pxe.c
+++ b/common/cmd_pxe.c
@@ -690,6 +690,7 @@
 	T_PROMPT,
 	T_INCLUDE,
 	T_FDT,
+	T_ONTIMEOUT,
 	T_INVALID
 };
 
@@ -718,6 +719,7 @@
 	{"initrd", T_INITRD},
 	{"include", T_INCLUDE},
 	{"fdt", T_FDT},
+	{"ontimeout", T_ONTIMEOUT,},
 	{NULL, T_INVALID}
 };
 
@@ -1016,10 +1018,8 @@
 
 	switch (t.type) {
 	case T_DEFAULT:
-		if (cfg->default_label)
-			free(cfg->default_label);
-
-		cfg->default_label = strdup(label->name);
+		if (!cfg->default_label)
+			cfg->default_label = strdup(label->name);
 
 		if (!cfg->default_label)
 			return -ENOMEM;
@@ -1179,6 +1179,7 @@
 			break;
 
 		case T_DEFAULT:
+		case T_ONTIMEOUT:
 			err = parse_sliteral(&p, &label_name);
 
 			if (label_name) {