moveconfig: fix error message in do_autoconf()

Move the % arch outside the double quote so that the missing toolchain
message is displayed correctly.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>