unoq: fix: reversed A4 and A5 ADC channels and clarify pin assignments

Correct the io-channels ordering so that A4 maps to PC1 (ADC1 Channel 2) and
A5 maps to PC0 (ADC1 Channel 1).

The corresponding channels can be found in the STM datasheet on page 111. Also,
add some comments to clarify which pins are being used.

Author: JoanVC100

variants/arduino_uno_q_stm32u585xx/arduino_uno_q_stm32u585xx.overlay

@@ -313,12 +313,12 @@
 		control-gpios = <&gpiog 13 GPIO_ACTIVE_HIGH>;    /* Internal SPI RDY */
 		analog-switch-gpios = <&gpioa 2 GPIO_ACTIVE_HIGH>;    /* Analog switch for VREF */
 
-		io-channels =	<&adc1 9>,
-				<&adc1 10>,
-				<&adc1 11>,
-				<&adc1 12>,
-				<&adc1 1>,
-				<&adc1 2>;
+		io-channels =	<&adc1 9>,     /* A0 - PA4 */
+				<&adc1 10>,   /* A1 - PA5 */
+				<&adc1 11>,   /* A2 - PA6 */
+				<&adc1 12>,   /* A3 - PA7 */
+				<&adc1 2>,    /* A4 - PC1 */
+				<&adc1 1>;    /* A5 - PC0 */
 
 		dac = <&dac1>;
 		dac-channels = <1>, <2>;