ARM: dts: imx6sx: Describe the default LCDIF1 parent

A suitable default for the LCDIF parent is the PLL5 clock, so
describe it in the device tree.

The imx6sx clock driver harcodes PLL5 as the LCDIF1 parent, but
in preparation for removing such hardcoding, describe the parent
relationship via devicetree.

There are some boards that may want to use a different parent
for the LCDIF due to EMI reasons, for example.

With this approch, the user can change the LCDIF parent in the board
devicetree if needed.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx6sx.dtsi

@@ -1306,6 +1306,10 @@ lcdif1: lcdif@2220000 {
 						 <&clks IMX6SX_CLK_LCDIF_APB>,
 						 <&clks IMX6SX_CLK_DISPLAY_AXI>;
 					clock-names = "pix", "axi", "disp_axi";
+					assigned-clocks = <&clks IMX6SX_CLK_LCDIF1_PRE_SEL>,
+							  <&clks IMX6SX_CLK_LCDIF1_SEL>;
+					assigned-clock-parents = <&clks IMX6SX_CLK_PLL5_VIDEO_DIV>,
+								 <&clks IMX6SX_CLK_LCDIF1_PODF>;
 					power-domains = <&pd_disp>;
 					status = "disabled";