pcmcia: re-route Cardbus IRQ to ISA on ti1130 bridges if necessary

As the PCI irq pin of the ti1130 pcmcia bridge is not connected (at
least on some old IBM Thinkpad 760ED notebooks), the Cardbus IRQ has
to be routed to an ISA irq.

Part 3 of a series to allow the ISA irq to be used for Cardbus devices
if the socket's PCI irq is unusable.

[linux@dominikbrodowski.net: split up the original patch, commit message,
 cleanup]

Signed-off-by: Jens Kuenzer <Jens.Kuenzer@fpga.homeip.net>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>