setup_board: move all wrapper gen code into one func

Makes the code flow easier to follow, and makes it easier to skip
wrapper generation if we so desire.

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

Change-Id: Ie7a1d387fb21a495c6a2da2c9147587743240929
Reviewed-on: https://gerrit.chromium.org/gerrit/33485
Reviewed-by: Zdenek Behan <zbehan@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
1 file changed