Voltage Control: add sysfs interface

Signed-off-by: faux123 <reioux@gmail.com>

Conflicts:
	drivers/cpufreq/cpufreq.c
Voltage Control: initial voltage control for MSM S4-Pro SOC

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	arch/arm/mach-msm/Kconfig
enable voltage control