Fix ssl-opt.sh test cases grepping for MFL configuration output

Use and grep for the new max in/out record payload length API instead.

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 1ec8f09..914286c 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -3164,6 +3164,13 @@
     else
         mbedtls_printf( "    [ Record expansion is unknown ]\n" );
 
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+    mbedtls_printf( "    [ Maximum incoming record payload length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_max_in_record_payload( &ssl ) );
+    mbedtls_printf( "    [ Maximum outgoing record payload length is %u ]\n",
+                    (unsigned int) mbedtls_ssl_get_max_out_record_payload( &ssl ) );
+#endif
+
 #if defined(MBEDTLS_SSL_ALPN)
     if( opt.alpn_string != NULL )
     {