ipmi: enable oem ipmi command for fan control

This enables building the OEM IPMI handler for fan control.  This
includes the ability to set it in manual mode, or check if it's in
fail-sade mode.

Tested: Verified that using host-side tool I was able to get and set the
mode for a zone, as well as check if a zone had fallen into failsade
mode.
Change-Id: I995407c089610692c7f6442f6e22f76689f4da1c
Signed-off-by: Patrick Venture <venture@google.com>
3 files changed