Voltage Control: add sysfs interface

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

Conflicts:
	drivers/cpufreq/cpufreq.c

Change-Id: Ie6e157c9f6477863e29c8d67e48444f33b184bbb
Enabling Voltage Control in cyanogen_mako_defconfig

Change-Id: Ie2fdab10d3694b1abad80ae3a71ea7d4444dc814