net: wget: let wget_with_dns work with dns disabled

net: wget: let wget_with_dns work with dns disabled

This was marked as TODO in the code:
 - Enable use of wget_with_dns even if CMD_DNS is disabled if
   the given uri has the ip address for the http server.
 - Move the check for CMD_DNS inside wget_with_dns.
 - Rename wget_with_dns to wget_do_request

Signed-off-by: Adriano Cordova <adrianox@gmail.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>