grub git: workaround debugedit problems

Debugedit errors out on bare metal binaries. The first version of this patch limited it to 64 bit targets, but the problem now shows up on 32 bit targets (minnowboard) as well.

Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>