cros_bundle_firmware: Move uboot handling code closer together

BUG=chromium:595715
BRANCH=none
TEST=none

Change-Id: I0c4321473bba06319a4553f8fb168ef04e7902a0
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/397619
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
1 file changed