init: switch to ondemand governor

-Due to changes in the nutella kernel, interactive is no
longer available. I would just remove this line as "ondemand"
is already the default governor, but the comment...
See: https://github.com/Meticulus/nutella_kernel_samsung_venturi/commit/0c5305009a49c4f2bd4653d57d5db850f948e1d0