Add support for unified builds

With unified builds we should obtain any needed configuration from the
master configuration. Update the init script to do this.

BUG=chromium:773898
TEST=manual on pyro, electro (not done yet)
Need to test on eve / other boards to check non-unibuild

Change-Id: I9fd31ab3eb0ea69abb732c7930e8e29f125e9675
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/721062
Reviewed-by: Dylan Reid <dgreid@chromium.org>
1 file changed