EDAC, mpc85xx: Make mpc85xx-pci-edac a platform device

EDAC, mpc85xx: Make mpc85xx-pci-edac a platform device

Originally the mpc85xx-pci-edac driver bound directly to the PCI
controller node.

Commit

  905e75c46dba ("powerpc/fsl-pci: Unify pci/pcie initialization code")

turned the PCI controller code into a platform device. Since we can't
have two drivers binding to the same device, the EDAC code was changed
to be called into as a library-style submodule. However, this doesn't
work if the EDAC driver is built as a module.

Commit

  8d8fcba6d1ea ("EDAC: Rip out the edac_subsys reference counting")

exposed another problem with this approach -- mpc85xx_pci_err_probe()
was being called in the same early boot phase that the PCI controller
is initialized, rather than in the device_initcall phase that the EDAC
layer expects. This caused a crash on boot.

To fix this, the PCI controller code now creates a child platform device
specifically for EDAC, which the mpc85xx-pci-edac driver binds to.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Daniel Axtens <dja@axtens.net>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: Jia Hongtao <B38951@freescale.com>
Cc: Jiri Kosina <jkosina@suse.com>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Masanari Iida <standby24x7@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Rob Herring <robh@kernel.org>
Link: http://lkml.kernel.org/r/1449774432-18593-1-git-send-email-scottwood@freescale.com
Signed-off-by: Borislav Petkov <bp@suse.de>