net: mscc: ocelot: Update DTS for Luton pcb90

Update device tree for luton to add support for luton pcb90.
This pcb has 24 ports from which 12 ports are connected to
SerDes6G.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>

include/dt-bindings/mscc/luton_data.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: (GPL-2.0+ OR MIT) */
+/*
+ * Copyright (c) 2019 Microsemi Corporation
+ */
+
+#ifndef _LUTON_DATA_H_
+#define _LUTON_DATA_H_
+
+#define SERDES6G(x)     (x)
+#define SERDES6G_MAX    SERDES6G(5)
+#define SERDES_MAX      (SERDES6G_MAX)
+
+/* similar with phy_interface_t */
+#define PHY_MODE_SGMII  2
+#define PHY_MODE_QSGMII 4
+
+#endif