ARM: dts: stm32: Add alternate pinmux for UART4 pins

Add another mux option for UART4 pins, this is used on DRC Compact board.

Signed-off-by: Marek Vasut <[e-mail]>
Cc: Alexandre Torgue <[e-mail]>
Cc: [e-mail]
To: [e-mail]
Signed-off-by: Alexandre Torgue <[e-mail]>

arch/arm/boot/dts/stm32mp15-pinctrl.dtsi

···
 		};
 	};
 
+	uart4_pins_d: uart4-3 {
+		pins1 {
+			pinmux = <STM32_PINMUX('A', 13, AF8)>; /* UART4_TX */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('B', 2, AF8)>; /* UART4_RX */
+			bias-disable;
+		};
+	};
+
+	uart4_idle_pins_d: uart4-idle-3 {
+		pins1 {
+			pinmux = <STM32_PINMUX('A', 13, ANALOG)>; /* UART4_TX */
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('B', 2, AF8)>; /* UART4_RX */
+			bias-disable;
+		};
+	};
+
+	uart4_sleep_pins_d: uart4-sleep-3 {
+		pins {
+			pinmux = <STM32_PINMUX('A', 13, ANALOG)>, /* UART4_TX */
+				 <STM32_PINMUX('B', 2, ANALOG)>; /* UART4_RX */
+		};
+	};
+
 	uart7_pins_a: uart7-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('E', 8, AF7)>; /* UART7_TX */