Currently the iop3xx platform support code assumes that RedBoot is the
bootloader and has already initialized the ATU.  Linux should handle this
initialization for three reasons:

1/ The memory map that RedBoot sets up is not optimal (page_to_dma and
virt_to_phys return different addresses).  The effect of this is that using
the dma mapping API for the internal bus dma units generates pci bus
addresses that are incorrect for the internal bus.

2/ Not all iop platforms use RedBoot

3/ If the ATU is already initialized it indicates that the iop is an add-in
card in another host, it does not own the PCI bus, and should not be
re-initialized.

Changelog:
* rather than change nr_controllers to zero, simply do not call
  pci_common_init

Cc: Lennert Buytenhek <kernel@wantstofly.org>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>