staging: iio: adc: ad7280a: don't cast type inside switch expression

The type promotion will kick in, so the comparison will work.

Signed-off-by: Slawomir Stepien <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/adc/ad7280a.c

···
 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 	unsigned int val;
 
-	switch ((u32)this_attr->address) {
+	switch (this_attr->address) {
 	case AD7280A_CELL_OVERVOLTAGE:
 		val = 1000 + (st->cell_threshhigh * 1568) / 100;
 		break;
···
 	if (ret)
 		return ret;
 
-	switch ((u32)this_attr->address) {
+	switch (this_attr->address) {
 	case AD7280A_CELL_OVERVOLTAGE:
 	case AD7280A_CELL_UNDERVOLTAGE:
 		val = ((val - 1000) * 100) / 1568; /* LSB 15.68mV */
···
 	val = clamp(val, 0L, 0xFFL);
 
 	mutex_lock(&st->lock);
-	switch ((u32)this_attr->address) {
+	switch (this_attr->address) {
 	case AD7280A_CELL_OVERVOLTAGE:
 		st->cell_threshhigh = val;
 		break;