to guess the pciide capabilities, rather than trying to guess it by ourselve.
Add preliminary support for the 686b (Ultra/100) guessed from FreeBSD/linux
driver (datasheet not publically available, I contacted via).
Let chip-specific map routine do the autoconf printf if ide_name is NULL
(they may have more details about the controller than we have in pciide_attach)
is the same for the Ultra/33 and Ultra/66 version, so test writability of
the U66 enable bit (idea from Chris Cappuccio).
Thanks to David Carrel for testings.
bouyer