Add a helper function for sysfs array stores

Signed-off-by: Curtis Menard <curtis.menard@gmail.com>
cpufreq-exynos: Make the voltage interfaces step dynamic

Gets rid of the hardcoded step counts in the voltage interfaces so we won't ever have to touch them again if we wish to change CPU frequency step counts.
Signed-off-by: Curtis Menard <curtis.menard@gmail.com>
Add OC options