[patch v2] iio: tsl4531: fix error handling in tsl4531_check_id()

[Dan Carpenter <dan.carpenter@oracle.com>]

tsl4531_check_id() returns 1 on "found", 0 on "not found" and negative
if there is an error.  The bug here is that the error handling, treats
errors as "found".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
v2: slightly different fix

diff --git a/drivers/iio/light/tsl4531.c b/drivers/iio/light/tsl4531.c
index 2697918..fca0cb0 100644
--- a/drivers/iio/light/tsl4531.c
+++ b/drivers/iio/light/tsl4531.c
@@ -180,7 +180,10 @@ static int tsl4531_probe(struct i2c_client *client,
 	data->client = client;
 	mutex_init(&data->lock);
 
-	if (!tsl4531_check_id(client)) {
+	ret = tsl4531_check_id(client);
+	if (ret < 0)
+		return ret;
+	if (ret = 0) {
 		dev_err(&client->dev, "no TSL4531 sensor\n");
 		return -ENODEV;
 	}