net: lwip/wget: don't print content size twice

net: lwip/wget: don't print content size twice

If wget_info->silent is set, we should not print anything.

If wget_info->silent we print the received content size.
Printing the value of the Content-Length header is redundant

For chunked transfer no Content-Length header is sent.
The content length is returned as HTTPC_CONTENT_LEN_INVALID by the LwIP
library. In this case we were incorrectly printing '4 GiB'.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Jerome Forissier <jerome.forissier@arm.com>