opos6uldev: migrate to DM_VIDEO

Migrate to DM_VIDEO, update the device tree and remove code that is no
longer necessary.

Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>

arch/arm/dts/imx6ul-opos6uldev-u-boot.dtsi

@@ -7,6 +7,12 @@
 
 #include "imx6ul-opos6ul-u-boot.dtsi"
 
+/ {
+	aliases {
+		display0 = &lcdif;
+	};
+};
+
 &aips1 {
 	u-boot,dm-spl;
 
@@ -15,6 +21,10 @@
 	};
 };
 
+&lcdif {
+	u-boot,dm-pre-proper;
+};
+
 &pinctrl_uart1 {
 	u-boot,dm-spl;
 };

arch/arm/dts/imx6ul-opos6uldev.dts

@@ -187,7 +187,7 @@
 	status = "okay";
 
 	display0: display0 {
-		bits-per-pixel = <32>;
+		bits-per-pixel = <18>;
 		bus-width = <18>;
 
 		display-timings {
@@ -202,7 +202,7 @@
 				hsync-len = <64>;
 				vsync-len = <4>;
 				de-active = <1>;
-				pixelclk-active = <0>;
+				pixelclk-active = <1>;
 			};
 		};
 	};