ARM: dts: imx6sx: Add LCDIF compatible strings

imx6sx has the same LCDIF controller IP as in mx28, so add the proper
compatible strings.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>

arch/arm/boot/dts/imx6sx.dtsi

@@ -1065,6 +1065,7 @@ csi2: csi@0221c000 {
 				};
 
 				lcdif1: lcdif@02220000 {
+					compatible = "fsl,imx6sx-lcdif", "fsl,imx28-lcdif";
 					reg = <0x02220000 0x4000>;
 					interrupts = <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>;
 					clocks = <&clks IMX6SX_CLK_LCDIF1_PIX>,
@@ -1075,6 +1076,7 @@ lcdif1: lcdif@02220000 {
 				};
 
 				lcdif2: lcdif@02224000 {
+					compatible = "fsl,imx6sx-lcdif", "fsl,imx28-lcdif";
 					reg = <0x02224000 0x4000>;
 					interrupts = <GIC_SPI 6 IRQ_TYPE_LEVEL_HIGH>;
 					clocks = <&clks IMX6SX_CLK_LCDIF2_PIX>,