MINOR: ssl: switch to conn_get_dst() to retrieve the destination address

This replaces conn_get_to_addr() and the subsequent check.
diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 62b85d1..9b53a91 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -2083,8 +2083,7 @@
 	unsigned int key;
 	struct connection *conn = SSL_get_ex_data(ssl, ssl_app_data_index);
 
-	conn_get_to_addr(conn);
-	if (conn->flags & CO_FL_ADDR_TO_SET) {
+	if (conn_get_dst(conn)) {
 		key = ssl_sock_generated_cert_key(&conn->addr.to, get_addr_len(&conn->addr.to));
 		if (ssl_sock_assign_generated_cert(key, bind_conf, ssl))
 			return 1;