Change script to solve G_NEXT_SRV_RSA not set issue

Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index dbe9771..8d72c4e 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -91,6 +91,7 @@
     G_NEXT_SRV_RSA="$GNUTLS_NEXT_SERV --x509certfile data_files/server2.crt --x509keyfile data_files/server2.key"
 else
     G_NEXT_SRV=false
+    G_NEXT_SRV_RSA=false
 fi
 
 if [ -n "${GNUTLS_NEXT_CLI:-}" ]; then