include: add SPDX GPL-2.0-only license tags where applicable ...

Interpret "GPLv2" as "GPLv2 only".

Signed-off-by: Roland Hieber <rohieb@rohieb.name>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

of: mtd: Import of_get_nand_ecc_{step_size, strength} from Linux ...

This imports DT helpers for MTD ECC step size and strength from
Linux kernel.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

of: add mtd of helpers ...

Directly taken from the kernel

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>