ssl-opt.sh: Force TLS 1.2 on server for TLS 1.2 specific tests
ssl-opt.sh: Force TLS 1.2 on server for TLS 1.2 specific tests

Force TLS 1.2 on OpenSSL/GnuTLS server
for TLS 1.2 specific tests.

Signed-off-by: Ronald Cron <b35ff5b7ca26c4ae9b66b92f2cf34224c8e26b08@arm.com>

Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls