net: add fastboot TCP support

Known limitations are
1. fastboot reboot doesn't work (answering OK but not rebooting)
2. flashing isn't supported (TCP transport only limitation)

The command syntax is
fastboot tcp

Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
Cc: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
Cc: Simon Glass <sjg@chromium.org>
Сс: Joe Hershberger <joe.hershberger@ni.com>
Сс: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/net/fastboot_tcp.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (C) 2023 The Android Open Source Project
+ */
+
+#ifndef __NET_FASTBOOT_TCP_H__
+#define __NET_FASTBOOT_TCP_H__
+
+/**
+ * Wait for incoming tcp fastboot comands.
+ */
+void fastboot_tcp_start_server(void);
+
+#endif /* __NET_FASTBOOT_TCP_H__ */