[media] doc-rst: Fix license for the media books

The kAPI, v4l-drivers and dvb-drivers never used the
GNU FDL license. The addition of such license header were
just due to copy-and-paste. So, let's fix it.

As the media_kapi were part of device-drivers.tmp, it is
under GPL v2+.

The other two books is an agregation of files without any
license explicitly specified. So, they're all bound to the
Kernel's COPYING license. So, they're GPL v2 only.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/media/dvb-drivers/index.rst

@@ -8,11 +8,16 @@ Linux Digital TV driver-specific documentation
 
 **Copyright** |copy| 2001-2016 : LinuxTV Developers
 
-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. A copy of
-the license is included in the chapter entitled "GNU Free Documentation
-License".
+This documentation is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the Free
+Software Foundation version 2 of the License.
+
+This program 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 for
+more details.
+
+For more details see the file COPYING in the source distribution of Linux.
 
 .. class:: toc-title
 

Documentation/media/media_kapi.rst

@@ -8,11 +8,17 @@ Media subsystem kernel internal API
 
 **Copyright** |copy| 2009-2016 : LinuxTV Developers
 
-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. A copy of
-the license is included in the chapter entitled "GNU Free Documentation
-License".
+This documentation is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2 of the License, or (at your option) any
+later version.
+
+This program 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 for
+more details.
+
+For more details see the file COPYING in the source distribution of Linux.
 
 .. class:: toc-title
 

Documentation/media/v4l-drivers/index.rst

@@ -8,11 +8,16 @@ Video4Linux (V4L)  driver-specific documentation
 
 **Copyright** |copy| 1999-2016 : LinuxTV Developers
 
-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. A copy of
-the license is included in the chapter entitled "GNU Free Documentation
-License".
+This documentation is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the Free
+Software Foundation version 2 of the License.
+
+This program 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 for
+more details.
+
+For more details see the file COPYING in the source distribution of Linux.
 
 .. class:: toc-title