boards: st: nucleo_wba55cg: add mcuboot-{led0,button0} aliases

This adds DT aliases for LED and button used in recovery mode of the
MCUboot bootloader, on the 'nucleo_wba55cg' board.

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>

boards/st/nucleo_wba55cg/nucleo_wba55cg.dts

@@ -69,6 +69,8 @@
 		sw0 = &user_button_1;
 		sw1 = &user_button_2;
 		sw2 = &user_button_3;
+		mcuboot-led0 = &blue_led_1;
+		mcuboot-button0 = &user_button_1;
 	};
 };