Staging: gdm72xx: underflow bug in gdm_wimax_ioctl_get_data()

"size" here should be unsigned, otherwise we might end up trying to copy
negative bytes in gdm_wimax_ioctl_get_data() resulting in an information
leak.

Reported-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm72xx/wm_ioctl.h

@@ -74,12 +74,12 @@ struct fsm_s {
 };
 
 struct data_s {
-	int	size;
+	unsigned int size;
 	void	*buf;
 };
 
 struct udata_s {
-	int		size;
+	unsigned int	size;
 	void __user	*buf;
 };