ARM: dts: stm32: add ADC pins used on stm32mp157a-dk1

Define pins that can be used for ADC on stm32mp157a-dk1 board:
- AIN connector has ADC input pins
- USB Type-C CC1 & CC2 pins (e.g. in18, in19)

Signed-off-by: Fabrice Gasnier <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

arch/arm/boot/dts/stm32mp157-pinctrl.dtsi

···
 				status = "disabled";
 			};
 
+			adc12_ain_pins_a: adc12-ain-0 {
+				pins {
+					pinmux = <STM32_PINMUX('C', 3, ANALOG)>, /* ADC1 in13 */
+						 <STM32_PINMUX('F', 12, ANALOG)>, /* ADC1 in6 */
+						 <STM32_PINMUX('F', 13, ANALOG)>, /* ADC2 in2 */
+						 <STM32_PINMUX('F', 14, ANALOG)>; /* ADC2 in6 */
+				};
+			};
+
+			adc12_usb_cc_pins_a: adc12-usb-cc-pins-0 {
+				pins {
+					pinmux = <STM32_PINMUX('A', 4, ANALOG)>, /* ADC12 in18 */
+						 <STM32_PINMUX('A', 5, ANALOG)>; /* ADC12 in19 */
+				};
+			};
+
 			cec_pins_a: cec-0 {
 				pins {
 					pinmux = <STM32_PINMUX('A', 15, AF4)>;