sync the northbridge.c with other family.

Change-Id: Ice4d0202590fca0169dcda2770ca6add166b5c13
Signed-off-by: Zheng Bao <zheng.bao@amd.com>
Signed-off-by: zbao <fishbaozi@gmail.com>
Reviewed-on: http://review.coreboot.org/1262
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
3 files changed