configure.ac: Remove use of PKCS11_HELPER_LIBS in mbedTLS checks

configure.ac: Remove use of PKCS11_HELPER_LIBS in mbedTLS checks

This code was copied over and over since many years,
since commit 9a3f670248d6f519a399e65a7232e2196b5115db
("Fixed autoconf script to properly detect missing pkcs11
with polarssl"). It is unclear what exact purpose it
served back then but probably it is obsolete. It is
definitely wrong since it means that you get
PKCS11_HELPER_LIBS even if you do not specify
--enable-pkcs11.

Change-Id: I317be5253d6563906dd3826421dc81f737beba76
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org>
Message-Id: <20250716151857.385959-1-frank@lichtenheld.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg32187.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>