via-ircc: Use pci_{get, set}_drvdata() instead of static pointer variable

via-ircc still maintains its own array of device pointers in Linux 2.4
style.  Worse, it always uses index 0, so it will crash if there are
multiple suitable devices in the system.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>