Align forced ciphersuite with test description

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 05978cd..0edb626 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -9019,7 +9019,7 @@
              crt_file=data_files/server8_int-ca2.crt \
              key_file=data_files/server8.key \
              exchanges=2 renegotiation=1 renegotiate=1 \
-             force_ciphersuite=TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256 \
+             force_ciphersuite=TLS-ECDHE-ECDSA-WITH-CHACHA20-POLY1305-SHA256 \
              hs_timeout=10000-60000 \
              mtu=512" \
             0 \