samples: sensor: stm32_temp_vbat: Update sample to use DEVICE_DT_GET_ONE

Update sample to use DEVICE_DT_GET_ONE to remove usage of DT_INST.

Signed-off-by: Benjamin Björnsson <benjamin.bjornsson@gmail.com>
diff --git a/samples/sensor/stm32_vbat_sensor/src/main.c b/samples/sensor/stm32_vbat_sensor/src/main.c
index 170c630..19041a5 100644
--- a/samples/sensor/stm32_vbat_sensor/src/main.c
+++ b/samples/sensor/stm32_vbat_sensor/src/main.c
@@ -9,17 +9,11 @@
 #include <zephyr/drivers/sensor.h>
 #include <zephyr/sys/printk.h>
 
-#if DT_HAS_COMPAT_STATUS_OKAY(st_stm32_vbat)
-#define VBAT_NODE DT_INST(0, st_stm32_vbat)
-#else
-#error "Could not find a compatible vbat sensor"
-#endif
-
 void main(void)
 {
 	struct sensor_value val;
 	int rc;
-	const struct device *dev = DEVICE_DT_GET(VBAT_NODE);
+	const struct device *dev = DEVICE_DT_GET_ONE(st_stm32_vbat);
 
 	if (!device_is_ready(dev)) {
 		printk("VBAT sensor is not ready\n");