ARM: dts: stm32: Update UART4 pin states on stm32mp15xx-dkx

Add sleep and idle states to uart4 pin configuration.
Signed-off-by: Erwan Le Ray <erwan.leray@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/boot/dts/stm32mp15xx-dkx.dtsi

@@ -584,8 +584,10 @@ timer@11 {
 };
 
 &uart4 {
-	pinctrl-names = "default";
+	pinctrl-names = "default", "sleep", "idle";
 	pinctrl-0 = <&uart4_pins_a>;
+	pinctrl-1 = <&uart4_sleep_pins_a>;
+	pinctrl-2 = <&uart4_idle_pins_a>;
 	status = "okay";
 };