setup_board: use sudo_multi in more places

This gives a side speed up and a slight clean up.

While we're here, merge a few commands (like mkdirs).

BUG=chromium-os:34519
TEST=`./setup_board --board=lumpy` output looked ok
TEST=`cbuildbot {x86,amd64,arm}-generic-full chromiumos-sdk` worked

Change-Id: I8d03448e2df549e76d320cc23ab9d36242c3b118
Reviewed-on: https://gerrit.chromium.org/gerrit/33486
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Zdenek Behan <zbehan@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
1 file changed