This is used when the BMC isn't running any code and thus has
to be initialized by the host.

The code originates from Aspeed (Y.C. Chen) and has been cleaned
up for coding style purposes by BenH.
Signed-off-by: NY.C. Chen <yc_chen@aspeedtech.com>
Acked-by: NJoel Stanley <joel@jms.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NDave Airlie <airlied@redhat.com>