staging: iio: Remove unnecessary cast on void pointer

The following Coccinelle script was used to detect this:
@r@
expression x;
void* e;
type T;
identifier f;
@@
(
  *((T *)e)
|
  ((T *)x)[...]
|
  ((T*)x)->f
|

- (T*)
  e
)
Signed-off-by: Arushi Singhal <arushisinghal19971997@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/adc/ad7816.c

@@ -254,7 +254,7 @@ static const struct attribute_group ad7816_attribute_group = {
 static irqreturn_t ad7816_event_handler(int irq, void *private)
 {
 	iio_push_event(private, IIO_EVENT_CODE_AD7816_OTI,
-		       iio_get_time_ns((struct iio_dev *)private));
+		       iio_get_time_ns(private));
 	return IRQ_HANDLED;
 }