iio: core: Add misssing braces

Silences the following checkpatch warning:
WARNING: sizeof *iio_attr should be sizeof(*iio_attr)

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index e4780b4..18f72e3 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -685,7 +685,7 @@
 	int ret;
 	struct iio_dev_attr *iio_attr, *t;
 
-	iio_attr = kzalloc(sizeof *iio_attr, GFP_KERNEL);
+	iio_attr = kzalloc(sizeof(*iio_attr), GFP_KERNEL);
 	if (iio_attr == NULL) {
 		ret = -ENOMEM;
 		goto error_ret;