This introduces a CHROMEEC_SOURCE variable used for indicating the CrOS
EC source path, with a fallback to 3rdparty/chromeec.
This allows specifying an external path for the CrOS EC source path.
Change-Id: I9792c7f21597127a385b961b65a00d44cfa37146
Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
Reviewed-on: https://review.coreboot.org/15765
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>