[PATCH] powerpc: pci_address_to_pio fix

This fixes pci_address_to_pio() to return an unsigned long (to be safe)
and fixes a bug in the implementation that caused it to return a bogus
IO port number

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>