PM / OPP: Parse 'opp-supported-hw' binding

OPP bindings allow a platform to enable OPPs based on the version of the
hardware they are used for.

Add support to the OPP-core to parse these bindings, by introducing
dev_pm_opp_{set|put}_supported_hw() APIs.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>