video: of: display_timing: add doubleclk flag

Signed-off-by: NSteffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: NDave Airlie <airlied@redhat.com>

Documentation/devicetree/bindings/video/display-timing.txt

@@ -34,6 +34,7 @@ optional properties:
 			- ignored     = ignored
  - interlaced (bool): boolean to enable interlaced mode
  - doublescan (bool): boolean to enable doublescan mode
+ - doubleclk (bool): boolean to enable doubleclock mode
 
 All the optional properties that are not bool follow the following logic:
     <1>: high active

drivers/video/of_display_timing.c

@@ -98,6 +98,8 @@ static struct display_timing *of_get_display_timing(const struct device_node
 		dt->flags |= DISPLAY_FLAGS_INTERLACED;
 	if (of_property_read_bool(np, "doublescan"))
 		dt->flags |= DISPLAY_FLAGS_DOUBLESCAN;
+	if (of_property_read_bool(np, "doubleclk"))
+		dt->flags |= DISPLAY_FLAGS_DOUBLECLK;
 
 	if (ret) {
 		pr_err("%s: error reading timing properties\n",