pata_sis: Clean up using cable_detect methods

This changeset revolves around the fact that all the SiS controllers have
the same enable bits, but differing cable detection methods. Previously
that meant each type had its own error_handler methods. Instead we can
now implement different ->cable_detect methods and share a single
error_handler which does the filtering by enable bits.

In addition we had some auto const arrays that should be static const. I'm
not sure if gcc already treats them intelligently but adding the static
will make sure.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>