pm8xxx-vibrator: exposed sysfs to modify voltage level

sysfs path: sys/devices/platform/msm_ssbi.0/pm8058-core/pm8xxx-vib/amp

credit: ngvincent
cpufreq: Kconfig option to sync scaling across CPU cores

Allow compatibility with CM CPU Performances settings which only
set cpu governor and min/max frequencies on the first cpu core

Change-Id: Id9ab81ba730180a3caabcf17e8913b9b561664a5