[PATCH] fix via586 irq routing for pirq 5

[PATCH] fix via586 irq routing for pirq 5

Fix interrupt 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

Cc: Daniel Paschka <[email protected]>
Cc: Adrian Bunk <[email protected]>
Signed-off-by: Daniel Ritz <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>