ARM: imx6: DHCOM i.MX6 PDK: Fix usb-otg VBUS regulator

During the conversion of this board to DM_REGULATOR, usb-mass-storage
was broken and started failing with the following error:

        => ums 0 mmc 2
        UMS: LUN 0, dev 2, hwpart 0, sector 0x0, count 0xe90000
        Error enabling VBUS supply
        g_dnl_register: failed!, error: -38
        g_dnl_register failed

Fix this by adding the relevant GPIO to the regulator node.

Fixes: 4ca99fe81aea ("ARM: imx: dh-imx6: Enable DM regulator")
Signed-off-by: Harald Seiler <hws@denx.de>
diff --git a/arch/arm/dts/imx6qdl-dhcom-pdk2-u-boot.dtsi b/arch/arm/dts/imx6qdl-dhcom-pdk2-u-boot.dtsi
index a54e421..32128d4 100644
--- a/arch/arm/dts/imx6qdl-dhcom-pdk2-u-boot.dtsi
+++ b/arch/arm/dts/imx6qdl-dhcom-pdk2-u-boot.dtsi
@@ -3,6 +3,8 @@
  * Copyright (C) 2020 Harald Seiler <hws@denx.de>
  */
 
+#include "imx6qdl-dhcom-u-boot.dtsi"
+
 / {
 	fec_vio: regulator-fec {
 		compatible = "regulator-fixed";