Revert "[POWERPC] Autodetect serial console on efika"

This reverts commit 9414715a7bbb45450015e9bc2676d85d919d08d4,
at Olaf Hering's request:

> Paul, please discard this patch. The optional graphics card may have
> also device_type 'serial' if it is in VGA mode.
> I will send an updated patch later.
1 file changed