Inagua: Synchronize AMD/inagua mainboard.

Inagua: Synchronize AMD/inagua mainboard.

AMD/persimmon mainboard code is derived from AMD/inagua mainbard.
Persimmom update a lot in the last few month, sync these modification to inagua.

Change-Id: Ia038e5a2b9550fe81bb075f31e30b98354758e9e
Signed-off-by: Kerry Sheh <shekairui@gmail.com>
Signed-off-by: Kerry Sheh <kerry.she@amd.com>
Reviewed-on: http://review.coreboot.org/542
Tested-by: build bot (Jenkins)
Reviewed-by: Marc Jones <marcj303@gmail.com>