samples: nrf52: onoff-app: use dts-generated defines

This commit updates the onoff-app sample to use the dts-generated
defines instead of the aliases in board.h.

Signed-off-by: Emanuele Di Santo <emdi@nordicsemi.no>
diff --git a/samples/boards/nrf52/mesh/onoff-app/src/main.c b/samples/boards/nrf52/mesh/onoff-app/src/main.c
index e7911ed..956f41a 100644
--- a/samples/boards/nrf52/mesh/onoff-app/src/main.c
+++ b/samples/boards/nrf52/mesh/onoff-app/src/main.c
@@ -643,7 +643,7 @@
 	/* Initialize button count timer */
 	k_timer_init(&sw.button_timer, button_cnt_timer, NULL);
 
-	sw_device = device_get_binding(SW0_GPIO_NAME);
+	sw_device = device_get_binding(SW0_GPIO_CONTROLLER);
 	gpio_pin_configure(sw_device, SW0_GPIO_PIN,
 			  (GPIO_DIR_IN | GPIO_INT | GPIO_INT_EDGE |
 			   GPIO_INT_ACTIVE_LOW | GPIO_PUD_PULL_UP));
@@ -666,10 +666,10 @@
 	gpio_pin_enable_callback(sw_device, SW3_GPIO_PIN);
 
 	/* Initialize LED's */
-	init_led(0, LED0_GPIO_PORT, LED0_GPIO_PIN);
-	init_led(1, LED1_GPIO_PORT, LED1_GPIO_PIN);
-	init_led(2, LED2_GPIO_PORT, LED2_GPIO_PIN);
-	init_led(3, LED3_GPIO_PORT, LED3_GPIO_PIN);
+	init_led(0, LED0_GPIO_CONTROLLER, LED0_GPIO_PIN);
+	init_led(1, LED1_GPIO_CONTROLLER, LED1_GPIO_PIN);
+	init_led(2, LED2_GPIO_CONTROLLER, LED2_GPIO_PIN);
+	init_led(3, LED3_GPIO_CONTROLLER, LED3_GPIO_PIN);
 
 	/* Initialize the Bluetooth Subsystem */
 	err = bt_enable(bt_ready);