boards: stm32: Correct Arduino header on Nucleo WL55JC

There appears to be a typo in the arduino header .dtsi
compared to UM2592 and physical hardware.

Signed-off-by: John Bason Mitchell <johnbasonmitchell@gmail.com>

Author: zbas

boards/st/nucleo_wl55jc/arduino_r3_connector.dtsi

@@ -30,8 +30,8 @@
 			   <17 0 &gpioa 7 0>,	/* D11 */
 			   <18 0 &gpioa 6 0>,	/* D12 */
 			   <19 0 &gpioa 5 0>,	/* D13 */
-			   <20 0 &gpiob 11 0>,	/* D14 */
-			   <21 0 &gpiob 12 0>;	/* D15 */
+			   <20 0 &gpioa 11 0>,	/* D14 */
+			   <21 0 &gpioa 12 0>;	/* D15 */
 	};
 };