treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arm: initial machine port for artpec-6 SoC

Basic machine port for the Artpec-6 SoC from Axis
Communications.

Signed-off-by: Lars Persson <larper@axis.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Olof Johansson <olof@lixom.net>