misc.c: remove unused code

misc.c: remove unused code

Commit

  3a4fb1 "Ensure --auth-nocache is handled during renegotiation"

has changed the behavior of set_auth_token(), but left unused parameter

  struct user_pass *up

Remove this parameter and amend comments accordingly. Also remove
unused function definition from misc.h.

Signed-off-by: Lev Stipakov <lev@openvpn.net>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Change-Id: Ic440f2c8d46dfcb5ff41ba2f33bf28bb7286eec4
Message-Id: <20240329103739.28254-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg28503.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 4c71e816031f564f834df695b3fa717ea22720d2)