AMD - SP5100 - take SPI ownership (1/2)

Hi all

I tried with IMC activated on coreboot (Hudson chipset) and it works as
expected. Attached patch only tweaks messages and removes now redundant check
from sb600 SPI. If IMC is active and firmware handoff fails, then it exits with
fatal error.

Signed-off-by: Rudolf Marek <r.marek@assembler.cz>

It would be nice if someone else could test this (and dont forget to be able to
recover from bad flash)

Thanks
Rudolf