sandbox: Support wide-screen LCD emulation

Increase the LCD size to 1366x768.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/dts/sandbox.dts b/arch/sandbox/dts/sandbox.dts
index 82d186e..99b0f36 100644
--- a/arch/sandbox/dts/sandbox.dts
+++ b/arch/sandbox/dts/sandbox.dts
@@ -72,8 +72,8 @@
 
 	lcd {
 		compatible = "sandbox,lcd-sdl";
-		xres = <800>;
-		yres = <600>;
+		xres = <1366>;
+		yres = <768>;
 	};
 
 	gpio_a: gpios@0 {