fsp_broadwell_de: Add SMBus driver for ramstage

There is currently a SMBus driver implemented for soc/intel/broadwell
which nearly matches Broadwell-DE as well. Use this driver as template
and add minor modifications to make it work for Broadwell-DE. Support in
romstage is not available and can be added with a different patch.

Change-Id: I64649ceaa298994ee36018f5b2b0f5d49cf7ffd0
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/15617
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
5 files changed