This fixes: [    0.010000] cpu cpu0: Error -2 creating of_node link
... which you get for every CPU on all architectures that use
CONFIG_GENERIC_CPU_DEVICES.

In that case, driver_init() calls cpu_dev_init() before calling
of_core_init(). Then we get the callchain:

  cpu_dev_init()
    -> cpu_dev_register_generic()
    -> register_cpu(cpu, i)
    -> device_register(&cpu->dev)
    -> device_add(dev)
    -> device_add_class_symlinks(dev)

... in device_add_class_symlinks, we we dev->of_node, and call
sysfs_create_link(), which fails because we haven't called
of_core_init() to register the sysfs devicetree directory yet.
Signed-off-by: NWesley W. Terpstra <wesley@sifive.com>
[hch: updated the changelog based on review feedback]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NFrank Rowand <frowand.list@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>