dm ioctl: use uninitialized_var

drivers/md/dm-ioctl.c:1405: warning: 'param' may be used uninitialized in this function
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>

drivers/md/dm-ioctl.c

@@ -1402,7 +1402,7 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
 {
 	int r = 0;
 	unsigned int cmd;
-	struct dm_ioctl *param;
+	struct dm_ioctl *uninitialized_var(param);
 	ioctl_fn fn = NULL;
 	size_t param_size;