cpufreq: Add SFI based cpufreq driver support

This adds the SFI based cpu freq driver for some of the Intel's
Silvermont based Atom architectures like Z34xx and Z35xx.

Signed-off-by: Rudramuni, Vishwesh M <vishwesh.m.rudramuni@intel.com>
Signed-off-by: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Len Brown <len.brown@intel.com>

diff --cc arch/x86/include/uapi/asm/msr-index.h
Simple merge

diff --cc drivers/cpufreq/Kconfig.x86
Simple merge

diff --cc drivers/cpufreq/Makefile
Simple merge

diff --cc drivers/cpufreq/sfi-cpufreq.c
Simple merge