media: Documentation: staging/ipu3-imgu: Add license information

The driver documentation is under GPL v2 and the uAPI documentation under
GNU FDL 1.1+ (without invariant sections) or GPL v2.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/pixfmt-meta-intel-ipu3.rst

-.. -*- coding: utf-8; mode: rst -*-
+.. This file is dual-licensed: you can use it either under the terms
+.. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this
+.. dual licensing only applies to this file, and not this project as a
+.. whole.
+..
+.. a) This file is free software; you can redistribute it and/or
+..    modify it under the terms of the GNU General Public License version
+..    2.0 as published by the Free Software Foundation.
+..
+..    This file is distributed in the hope that it will be useful,
+..    but WITHOUT ANY WARRANTY; without even the implied warranty of
+..    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+..    GNU General Public License version 2.0 for more details.
+..
+.. Or, alternatively,
+..
+.. b) Permission is granted to copy, distribute and/or modify this
+..    document under the terms of the GNU Free Documentation License,
+..    Version 1.1 or any later version published by the Free Software
+..    Foundation, with no Invariant Sections, no Front-Cover Texts
+..    and no Back-Cover Texts. A copy of the license is included at
+..    Documentation/media/uapi/fdl-appendix.rst.
+..
+.. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections
 
 .. _v4l2-meta-fmt-params:
 .. _v4l2-meta-fmt-stat-3a:

Documentation/media/v4l-drivers/ipu3.rst

+.. SPDX-License-Identifier: GPL-2.0
+
 .. include:: <isonum.txt>
 
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