ARM: dts: stm32: Update pin states for uart4 on stm32mp157c-ed1

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/stm32mp157c-ed1.dts

@@ -353,8 +353,10 @@ timer@5 {
 };
 
 &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";
 };