ARM: dts: imx8mq-evk: Remove u-boot,off-on-delay-us property

Commit 247bbeb74c18 ("ARM: dts: imx8m: increase off-on delay on the SD Vcc
regulator") caused the imx8mq-evk board to not be able to store the
environment variables in the SD card.

Remove the u-boot,off-on-delay-us property to fix the regression.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
diff --git a/arch/arm/dts/imx8mq-evk-u-boot.dtsi b/arch/arm/dts/imx8mq-evk-u-boot.dtsi
index 44af663..2cfc12b 100644
--- a/arch/arm/dts/imx8mq-evk-u-boot.dtsi
+++ b/arch/arm/dts/imx8mq-evk-u-boot.dtsi
@@ -1,9 +1,5 @@
 // SPDX-License-Identifier: (GPL-2.0 OR MIT)
 
-&reg_usdhc2_vmmc {
-	u-boot,off-on-delay-us = <20000>;
-};
-
 &usdhc1 {
 	mmc-hs400-1_8v;
 };