OK so some automatic scripts were fixing the SPDX tags in
the mainline branch while we were patching other stuff,
and yeah it is more correct to have "GPL-2.0-only" rather
than "GPL-2.0" so let's conform to what is already upstream
so we don't end up getting the wrong license on the merged
result later.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>