arch: introduce architecture dependent common variables

Stefan and others have discussed their interest in only
including options in Kconfig that are directly associated
with building a coreboot image. There are variables that
are architecture dependent that are utilized in the
coreboot infrastructure. To meet that goal, introduce
<arch/cbconfig.h> header file which defines variables
for the coreboot infrastructure that are architecture
dependent but utilized in common infrastructure.

Change-Id: Ic4cb9e81bab042797539dce004db0f7ee8526ea6
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/14454
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)
6 files changed