sensor: dht: Fix multi-instance type handling

The DHT driver incorrectly assumes all sensor instances are the same
type as the first instance (dht@0). The data parsing logic uses a
hardcoded check of the devicetree property for instance 0, which
causes incorrect readings when different sensor models (e.g., DHT11
and DHT22) are used together.

This change stores the model type in each per-instance config struct
during initialization. The data parsing logic is updated to use this
per-instance flag, ensuring each sensor is handled correctly
according to its specific model.

Signed-off-by: John Shelton <moosery@gmail.com>

drivers/sensor/aosong/dht/dht.c

@@ -182,12 +182,13 @@ static int dht_channel_get(const struct device *dev,
 			   struct sensor_value *val)
 {
 	struct dht_data *drv_data = dev->data;
+	const struct dht_config *cfg = dev->config;
 
 	__ASSERT_NO_MSG(chan == SENSOR_CHAN_AMBIENT_TEMP
 			|| chan == SENSOR_CHAN_HUMIDITY);
 
 	/* see data calculation example from datasheet */
-	if (IS_ENABLED(DT_INST_PROP(0, dht22))) {
+	if (cfg->is_dht22) {
 		/*
 		 * use both integral and decimal data bytes; resulted
 		 * 16bit data has a resolution of 0.1 units
@@ -258,6 +259,7 @@ static int dht_init(const struct device *dev)
 											\
 	static const struct dht_config dht_config_##inst = {				\
 		.dio_gpio = GPIO_DT_SPEC_INST_GET(inst, dio_gpios),			\
+		.is_dht22 = DT_INST_PROP(inst, dht22),					\
 	};										\
 											\
 	SENSOR_DEVICE_DT_INST_DEFINE(inst, &dht_init, NULL,				\

drivers/sensor/aosong/dht/dht.h

@@ -19,6 +19,7 @@ struct dht_data {
 
 struct dht_config {
 	struct gpio_dt_spec dio_gpio;
+	bool is_dht22; /* true for DHT22, false for DHT11 */
 };
 
 #endif