[Eas-dev] alternative name for sched-dvfs

It was pointed out in today's technical syncup that sched-dvfs should rely on its own static key, and that static key should not indicate a dependency on EAS.

The static key was named sched_energy_freq. I've renamed/shortened it to sched_freq. I also think we should try and use this name for the feature in general since I believe less people are familiar with the term/acronym DVFS. A git grep -i dvfs suggests it's almost exclusively an ARM term, at least as far as the kernel source goes, with a little usage in sound codecs and GPU.

If anyone has a better name or concerns please share...

thanks, Steve