staging: iio_simple_dummy: fix module_param type

Fix the module_param "instances" type to uint, since the variable type
holding the value is unsigned.
Signed-off-by: Vladimirs Ambrosovs <rodriguez.twister@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/iio_simple_dummy.c

@@ -30,7 +30,7 @@
  * dummy devices are registered.
  */
 static unsigned instances = 1;
-module_param(instances, int, 0);
+module_param(instances, uint, 0);
 
 /* Pointer array used to fake bus elements */
 static struct iio_dev **iio_dummy_devs;