uio: add SPDX license tags

For those without any license text present or short reference
to GPL, add SPDX tag.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/uio/uio_hv_generic.c b/drivers/uio/uio_hv_generic.c
index c690d10..e401be8 100644
--- a/drivers/uio/uio_hv_generic.c
+++ b/drivers/uio/uio_hv_generic.c
@@ -1,12 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * uio_hv_generic - generic UIO driver for VMBus
  *
  * Copyright (c) 2013-2016 Brocade Communications Systems, Inc.
  * Copyright (c) 2016, Microsoft Corporation.
  *
- *
- * This work is licensed under the terms of the GNU GPL, version 2.
- *
  * Since the driver does not declare any device ids, you must allocate
  * id and bind the device to the driver yourself.  For example:
  *