at: Change when files are copied

The create_spdx code relies on patched code, if files are changed
or added during the do_configure phase they will be missed by the
create_spdx process. So we need to ensure files modifications/additions
happen in the do_patch phase.

Signed-off-by: Saul Wold <saul.wold@windriver.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 227c46fe)
Signed-off-by: Steve Sakoman <steve@sakoman.com>