ARM: dts: imx6qdl: Remove LCD.CONTRAST pinctrl from muxing

GPIO4_IO20 is unused on MBA6x, unless LVDS display is attached.
Remove the pinctrl for GPIO4_IO20, so it can be used otherwise.
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/nxp/imx/imx6qdl-mba6.dtsi

@@ -442,8 +442,6 @@ MX6QDL_PAD_EIM_A25__HDMI_TX_CEC_LINE 0x1f8b0
 
 	pinctrl_hog: hoggrp {
 		fsl,pins = <
-			MX6QDL_PAD_DI0_PIN4__GPIO4_IO20 0x0001b099
-
 			MX6QDL_PAD_ENET_RXD1__GPIO1_IO26 0x0001b099
 			MX6QDL_PAD_ENET_TXD1__GPIO1_IO29 0x0001b099
 			MX6QDL_PAD_ENET_TXD0__GPIO1_IO30 0x0001b099