sis190 check for ISA bridge on SiS966

sis190 driver assumes to find ISA only on SiS965.
similar fix is in sis900 driver, see bug report
http://bugs.debian.org/435547



Signed-off-by: maximilian attems <max@stro.at>
Signed-off-by: Jeff Garzik <jeff@garzik.org>