If ACPI doesn't find an irq listed, don't accept 0 as a valid PCI irq.
That zero just means that nothing else found any irq information either.

Fixes http://bugme.osdl.org/show_bug.cgi?id=4824



Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>