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>

drivers/fastboot/Kconfig

@@ -4,6 +4,13 @@ config FASTBOOT
 	bool
 	imply ANDROID_BOOT_IMAGE
 	imply CMD_FASTBOOT
+	help
+	  Fastboot is a protocol used in Android devices for
+	  communicating between the device and a computer during
+	  the bootloader stage. It allows the user to flash the
+	  device firmware and unlock the bootloader.
+	  More information about the protocol and usecases:
+	  https://android.googlesource.com/platform/system/core/+/refs/heads/master/fastboot/
 
 config USB_FUNCTION_FASTBOOT
 	bool "Enable USB fastboot gadget"
@@ -28,6 +35,13 @@ config UDP_FUNCTION_FASTBOOT_PORT
 	help
 	  The fastboot protocol requires a UDP port number.
 
+config TCP_FUNCTION_FASTBOOT
+	depends on NET
+	select FASTBOOT
+	bool "Enable fastboot protocol over TCP"
+	help
+	  This enables the fastboot protocol over TCP.
+
 if FASTBOOT
 
 config FASTBOOT_BUF_ADDR

drivers/fastboot/fb_common.c

@@ -15,7 +15,6 @@
 #include <command.h>
 #include <env.h>
 #include <fastboot.h>
-#include <net/fastboot.h>
 
 /**
  * fastboot_buf_addr - base address of the fastboot download buffer