powerpc/powermac: Convert PCI to use generic config accessors

Convert the powermac PCI driver to use the generic config access functions.

This changes accesses from (in|out)_(8|le16|le32) to readX/writeX variants.
I believe these should be equivalent for PCI config space accesses, but
confirmation would be nice.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: linuxppc-dev@lists.ozlabs.org