ARM: dts: stm32: add alternate pinmux for HDP pin and add HDP pinctrl node

Introduce hdp node to output a user defined value on port hdp2.
Add pinctrl nodes to be able to output this signal on one SoC pin.

Signed-off-by: Clément Le Goffic <clement.legoffic@foss.st.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250711-hdp-upstream-v7-7-faeecf7aaee1@foss.st.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

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

@@ -5,6 +5,14 @@
  */
 #include <dt-bindings/pinctrl/stm32-pinfunc.h>
 
+&hdp {
+	/omit-if-no-ref/
+	hdp2_gpo: hdp2-pins {
+		function = "gpoval2";
+		pins = "HDP2";
+	};
+};
+
 &pinctrl {
 	/omit-if-no-ref/
 	adc1_ain_pins_a: adc1-ain-0 {
@@ -731,6 +739,23 @@
 		};
 	};
 
+	/omit-if-no-ref/
+	hdp2_pins_a: hdp2-0 {
+		pins {
+			pinmux = <STM32_PINMUX('E', 13, AF0)>; /* HDP2 */
+			bias-disable;
+			drive-push-pull;
+			slew-rate = <2>;
+		};
+	};
+
+	/omit-if-no-ref/
+	hdp2_sleep_pins_a: hdp2-sleep-0 {
+		pins {
+			pinmux = <STM32_PINMUX('E', 13, ANALOG)>; /* HDP2 */
+		};
+	};
+
 	/omit-if-no-ref/
 	i2c1_pins_a: i2c1-0 {
 		pins {