bundle_firmware: run cbfstool through sh to enable variable expansion

For the cbfstool invocations controlled by the cbfs-files fmap.dts
attribute, run the command line through the shell so environment
variables are expanded.

BUG=chromium:48415
TEST=none

Change-Id: Ib4c69bf164d8441571c78ff8ed0987916c40501a
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/317600
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed