net: wget: add wget with dns utility function

Current wget takes the target uri in this format:
 "<http server ip>:<file path>"  e.g.) 192.168.1.1:/bar
The http server ip address must be resolved before
calling wget.

This commit adds the utility function runs wget with dhs.
User can call wget with the uri like "http://foo/bar

".

Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>