northbridge/intel: Add i89xx header file

The Intel northbridge must be paired with a southbridge. Add
the ii89xx southbridge header based on the config setting.

Change-Id: Ied708006310efaba31afe6977ab7e57fe4e5ceec
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-on: http://review.coreboot.org/12167
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)
2 files changed