PM / OPP: Add "opp-supported-hw" binding

We may want to enable only a subset of OPPs, from the bigger list of
OPPs, based on what version of the hardware we are running on. This
would enable us to not duplicate OPP tables for every version of the
hardware we support.

To enable that, this patch defines a new property 'opp-supported-hw'. It
can support any number of hierarchy levels of the versions the hardware
follows. And based on the selected hardware versions, we can pick only
the relevant OPPs at runtime.

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>