net: wget: Support non-default HTTP port

Currently the wget command is hard wired to HTTP port 80. This is
inconvenient, as it is extremely easy to start trivial HTTP server
as an unprivileged user using e.g. python http module to serve the
files, but such a server has to run on one of the higher ports:
"
$ python3 -m http.server -d $(pwd) 8080
"

Make it possible to configure HTTP server port the same way it is
possible to configure TFTP server port, using environment variable
'httpdstp' (similar to 'tftpdstp'). Retain port 80 as the default
fallback port. This way, users can start their own trivial server
and conveniently download whatever files they need into U-Boot.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>

doc/usage/cmd/wget.rst

@@ -16,7 +16,8 @@ Description
 The wget command is used to download a file from an HTTP server.
 
 wget command will use HTTP over TCP to download files from an HTTP server.
-Currently it can only download image from an HTTP server hosted on port 80.
+By default the destination port is 80 and the source port is pseudo-random.
+The environment variable *httpdstp* can be used to set the destination port.
 
 address
     memory address for the data downloaded

doc/usage/environment.rst

@@ -306,6 +306,10 @@ ethrotate
     anything other than "no", U-Boot does go through all
     available network interfaces.
 
+httpdstp
+    If this is set, the value is used for HTTP's TCP
+    destination port instead of the default port 80.
+
 netretry
     When set to "no" each network operation will
     either succeed or fail without retrying.