Barebox is not using this macro.

Linux commit 055efab killed this
macro, so let's remove it from barebox too.

I see another cc-ldoption in dts/scripts/Kbuild.include, but did not
touch it. In my understanding, the dts/ directory is synced with the
upstream devicetree-rebasing project [1].

[1] git://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>