rockchip: rock2: dts: use status = "okay" not ok

u-boot only recognize okay to enable a node (Linux seems to be more
lenient here). So use okay instead.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/rk3288-rock2-square.dts b/arch/arm/dts/rk3288-rock2-square.dts
index 8d7446f..34073c9 100644
--- a/arch/arm/dts/rk3288-rock2-square.dts
+++ b/arch/arm/dts/rk3288-rock2-square.dts
@@ -111,7 +111,7 @@
 };
 
 &gmac {
-	status = "ok";
+	status = "okay";
 };
 
 &hdmi {