iio: tsl4531: fix error handling in tsl4531_check_id()

The tsl4531_check_id() function returned 1 on "found" and 0 on "not
found" and negative error codes on failure.  This was non-standard and
bug prone.  The caller treated all non-zero values including error codes
as "found".

This patch fixes it by changing the tsl4531_check_id() to return zero on
success or a negative error code, and updates the caller.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/light/tsl4531.c

@@ -158,9 +158,9 @@ static int tsl4531_check_id(struct i2c_client *client)
 	case TSL45313_ID:
 	case TSL45315_ID:
 	case TSL45317_ID:
-		return 1;
-	default:
 		return 0;
+	default:
+		return -ENODEV;
 	}
 }
 
@@ -180,9 +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) {
 		dev_err(&client->dev, "no TSL4531 sensor\n");
-		return -ENODEV;
+		return ret;
 	}
 
 	ret = i2c_smbus_write_byte_data(data->client, TSL4531_CONTROL,