Don't allow everybody to change voltage settings.
Signed-off-by: NVasiliy Kulikov <segoon@openwall.com>
Acked-by: NKevin Hilman <khilman@ti.com>
Acked-by: NNishanth Menon <nm@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>