net/ethoc: add CONFIG_DM_ETH support

Extract reusable parts from ethoc_init, ethoc_set_mac_address,
ethoc_send and ethoc_receive, move the rest under #ifdef CONFIG_DM_ETH.
Add U_BOOT_DRIVER, eth_ops structure and implement required methods.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

include/dm/platform_data/net_ethoc.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2016 Cadence Design Systems Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#ifndef _ETHOC_H
+#define _ETHOC_H
+
+#include <net.h>
+
+#ifdef CONFIG_DM_ETH
+
+struct ethoc_eth_pdata {
+	struct eth_pdata eth_pdata;
+};
+
+#endif
+
+#endif /* _ETHOC_H */