fix interrput routing for via 586 bridges. pirq can be 5 which needs to be
mapped to INTD. but currently the access functions can handle only pirq 1-4.
this is similar to the other via chipsets where pirq 4 and 5 are both mapped
to INTD. fixes bugzilla #7490
Signed-off-by: Daniel Ritz <daniel.ritz@gmx.ch>
Signed-off-by: Adrian Bunk <bunk@stusta.de>