patman: Avoid changing the order of tags

patman collects tags that it sees in the commit and places them nicely
sorted at the end of the patch. However, this is not really necessary and
in fact is apparently not desirable.

Suggested-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Masahiro Yamada <yamada.m@jp.panasonic.com>