The 'stamp-base' and 'stamp-base-clean' related codes are no longer useful,
clean them up.
[YOCTO #8468]
(Bitbake rev: 7b4c42b315d4a26dd8f2ceb874a94737bf9f183e)
Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>