arm: dts: phycore-imx8mm-u-boot: Add wdog pinctrl entry

Add missing pinctrl entry in spl.

Signed-off-by: Teresa Remmet <t.remmet@phytec.de>
diff --git a/arch/arm/dts/phycore-imx8mm-u-boot.dtsi b/arch/arm/dts/phycore-imx8mm-u-boot.dtsi
index 91515b8..7c2dfb4 100644
--- a/arch/arm/dts/phycore-imx8mm-u-boot.dtsi
+++ b/arch/arm/dts/phycore-imx8mm-u-boot.dtsi
@@ -30,6 +30,10 @@
 	u-boot,dm-spl;
 };
 
+&pinctrl_wdog {
+	u-boot,dm-spl;
+};
+
 &gpio1 {
 	u-boot,dm-spl;
 };