Improve VIA K8M890 HT settings. Use recommended settings for ROMSIP and

Improve VIA K8M890 HT settings. Use recommended settings for ROMSIP and
for the transmit clock driving control. Unfortunately this is not enough
to make the HT1000 work reliably, therefore blacklist this for now in CPU
HT code. If ever anyone figure out what is wrong, it could be removed. The
downgrading now makes the board work on HT800, which is certainly better than
not at all with a HT1000 CPU.

Change-Id: I949bfd9b0b48ee12bd0234c2fb1deaaa773bd235
Signed-off-by: Rudolf Marek <r.marek@assembler.cz>
Reviewed-on: http://review.coreboot.org/68
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>