OPP: Adjust includes to remove of_device.h

Now that of_cpu_device_node_get() is defined in of.h, of_device.h is just
implicitly including other includes, and is no longer needed. Adjust the
include files with what was implicitly included by of_device.h (cpu.h and
of.h) and drop including of_device.h.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-18-581e2605fe47@kernel.org


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