PCI: VIA IRQ quirk behaviour change

The most recent VIA IRQ quirk changes have broken various VIA devices for
some users.  We are not able to add these devices to the blacklist as they
are also available in PCI-card form, and running the quirk on these devices
brings us back to square one (running the VIA quirk on non-VIA boards where
the quirk is not needed).

This patch, based on suggestions from Sergey Vlasov, implements a scheme
similar to but more restrictive than the scheme we had in 2.6.16 and
earlier.  It runs the quirk on all VIA hardware, but *only* if a VIA
southbridge was detected on the system.

To further reduce the amount of quirked devices, this patch includes a
change suggested by Linus at http://lkml.org/lkml/2005/9/27/113 This
ensures that devices bound to non-legacy IO-APIC interrupt lines are not
quirked.  We have made one change to Linus' suggestion: we do a comparison
of ">15" rather than ">=15", as 15 is still in the legacy interrupt range.

There is still a downside to this patch: if the user inserts a VIA PCI card
into a VIA-based motherboard, in some circumstances the quirk will also run
on the VIA PCI card.  This corner case is hard to avoid.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>