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>

[media] as102: promote it out of staging

This driver is stable and doesn't contain any really serious
issue. Move it out of staging.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>