ARM: dts: stm32: Add pinmux for USART1 pins on stm32mp15

Add a mux option for the USART1 pins.

This is used on the Phycore STM32MP1.
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

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

@@ -2273,6 +2273,33 @@ pins {
 		};
 	};
 
+	usart1_pins_a: usart1-0 {
+		pins1 {
+			pinmux = <STM32_PINMUX('A', 12, AF7)>; /* USART1_RTS */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('A', 11, AF7)>; /* USART1_CTS_NSS */
+			bias-disable;
+		};
+	};
+
+	usart1_idle_pins_a: usart1-idle-0 {
+		pins1 {
+			pinmux = <STM32_PINMUX('A', 12, ANALOG)>, /* USART1_RTS */
+				 <STM32_PINMUX('A', 11, AF7)>; /* USART1_CTS_NSS */
+		};
+	};
+
+	usart1_sleep_pins_a: usart1-sleep-0 {
+		pins {
+			pinmux = <STM32_PINMUX('A', 12, ANALOG)>, /* USART1_RTS */
+				 <STM32_PINMUX('A', 11, ANALOG)>; /* USART1_CTS_NSS */
+		};
+	};
+
 	usart2_pins_a: usart2-0 {
 		pins1 {
 			pinmux = <STM32_PINMUX('F', 5, AF7)>, /* USART2_TX */
@@ -2612,4 +2639,34 @@ pins2 {
 			bias-disable;
 		};
 	};
+
+	usart1_pins_b: usart1-1 {
+		pins1 {
+			pinmux = <STM32_PINMUX('Z', 7, AF7)>; /* USART1_TX */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <0>;
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('Z', 6, AF7)>; /* USART1_RX */
+			bias-disable;
+		};
+	};
+
+	usart1_idle_pins_b: usart1-idle-1 {
+		pins1 {
+			pinmux = <STM32_PINMUX('Z', 7, ANALOG)>; /* USART1_TX */
+		};
+		pins2 {
+			pinmux = <STM32_PINMUX('Z', 6, AF7)>; /* USART1_RX */
+			bias-disable;
+		};
+	};
+
+	usart1_sleep_pins_b: usart1-sleep-1 {
+		pins {
+			pinmux = <STM32_PINMUX('Z', 7, ANALOG)>, /* USART1_TX */
+				 <STM32_PINMUX('Z', 6, ANALOG)>; /* USART1_RX */
+		};
+	};
 };