ARM: dts: stm32: Add alternate pinmux for UART3 pins

Add another mux option for UART3 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

···
 		};
 	};
 
+	usart3_pins_e: usart3-4 {
+		pins1 {
+			pinmux = <STM32_PINMUX('B', 10, AF7)>, /* USART3_TX */
+				 <STM32_PINMUX('G', 8, AF8)>; /* USART3_RTS */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('B', 11, AF7)>, /* USART3_RX */
+				 <STM32_PINMUX('D', 11, AF7)>; /* USART3_CTS_NSS */
+			bias-pull-up;
+		};
+	};
+
+	usart3_idle_pins_e: usart3-idle-4 {
+		pins1 {
+			pinmux = <STM32_PINMUX('B', 10, ANALOG)>, /* USART3_TX */
+				 <STM32_PINMUX('D', 11, ANALOG)>; /* USART3_CTS_NSS */
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('G', 8, AF8)>; /* USART3_RTS */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+		pins3 {
+			pinmux = <STM32_PINMUX('B', 11, AF7)>; /* USART3_RX */
+			bias-pull-up;
+		};
+	};
+
+	usart3_sleep_pins_e: usart3-sleep-4 {
+		pins {
+			pinmux = <STM32_PINMUX('B', 10, ANALOG)>, /* USART3_TX */
+				 <STM32_PINMUX('G', 8, ANALOG)>, /* USART3_RTS */
+				 <STM32_PINMUX('D', 11, ANALOG)>, /* USART3_CTS_NSS */
+				 <STM32_PINMUX('B', 11, ANALOG)>; /* USART3_RX */
+		};
+	};
+
 	usbotg_hs_pins_a: usbotg-hs-0 {
 		pins {
 			pinmux = <STM32_PINMUX('A', 10, ANALOG)>; /* OTG_ID */