coreboot: Support alternative locations for CBFS.

The Google builds of SeaBIOS place the CBFS data in a non-standard
location.  Add a config parameter to support non-standard locations.
This is based on a patch from Stefan Reinauer <reinauer@chromium.org>
in the Chromium seabios repo (commit 60534ec785).

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
2 files changed