generate_auth_token: simplify code

generate_auth_token: simplify code

The previous code went through some hoops
to avoid compiler warnings. But there is
a much easier way by just telling it
exactly what you want to do.

Also fix typo in variable name while I'm
here.

Change-Id: Icc86334b26ba1fcc20f4cd03644018d1d16796e3
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Message-Id: <20240910170005.5586-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29178.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>