staging/iio: Use correct argument for sizeof

found with coccicheck
sizeof when applied to a pointer typed expression gives the size of
the pointer

The semantic patch that makes this output is available
in scripts/coccinelle/misc/noderef.cocci.

More information about semantic patching is available at
http://coccinelle.lip6.fr/

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/iio_hwmon.c

@@ -93,7 +93,7 @@ static int iio_hwmon_probe(struct platform_device *pdev)
 	while (st->channels[st->num_channels].indio_dev)
 		st->num_channels++;
 
-	st->attrs = kzalloc(sizeof(st->attrs) * (st->num_channels + 1),
+	st->attrs = kzalloc(sizeof(*st->attrs) * (st->num_channels + 1),
 			    GFP_KERNEL);
 	if (st->attrs == NULL) {
 		ret = -ENOMEM;