of: Move of_platform_register_reconfig_notifier() into DT core

There's no reason the generic platform bus code needs to call
of_platform_register_reconfig_notifier(). The notifier can be setup
before the platform bus is. Let's move it into of_core_init() which is
called just before platform_bus_init() instead to keep more of the DT
bits in the DT code.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230717143718.1715773-1-robh@kernel.org


Signed-off-by: Rob Herring <robh@kernel.org>