ARM: dts: imx7s: Fix lcdif compatible

imx7d-lcdif is compatible to imx6sx-lcdif. MXSFB_V6 supports overlay
by using LCDC_AS_CTRL register. This registers used by overlay plane:
* LCDC_AS_CTRL
* LCDC_AS_BUF
* LCDC_AS_NEXT_BUF
are listed in i.MX7D RM as well.

Signed-off-by: Alexander Stein <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>

Author: tq-steina

arch/arm/boot/dts/nxp/imx/imx7s.dtsi

@@ -815,7 +815,7 @@
 			};
 
 			lcdif: lcdif@30730000 {
-				compatible = "fsl,imx7d-lcdif", "fsl,imx28-lcdif";
+				compatible = "fsl,imx7d-lcdif", "fsl,imx6sx-lcdif";
 				reg = <0x30730000 0x10000>;
 				interrupts = <GIC_SPI 5 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX7D_LCDIF_PIXEL_ROOT_CLK>,