Add explicit license headers to all files in src/device.

Add explicit license headers to all files in src/device.

For files derived from the Linux kernel we merely add a small header
which states the origin of the file and the copyright owners of the
modifications to the file.
We know all files from Linux are licensed under the GPLv2.

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2615 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1