cpufreq: dt: Add support for interconnect bandwidth scaling

In addition to clocks and regulators, some devices can scale the bandwidth
of their on-chip interconnect - for example between CPU and DDR memory. Add
support for that, so that platforms which support it can make use of it.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
[ Viresh: Reused dev_pm_opp_of_find_icc_paths(). Also drop the depends
	  on from Kconfig. ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

fixup! cpufreq: dt: Add support for interconnect bandwidth scaling