CPUFreq drivers that use clock frameworks interface,i.e. clk_get_rate(),
to get CPUs clk rate, have similar sort of code used in most of them.

This patch adds a generic ->get() which will do the same thing for them.
All those drivers are required to now is to set .get to cpufreq_generic_get()
and set their clk pointer in policy->clk during ->init().
Acked-by: NHans-Christian Egtvedt <egtvedt@samfundet.no>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>