Revert "arm: Add auto hotplug driver This driver is simple and cheap and aims to avoid unnecessary hotplug events and unnecessary task migrations. The design is simple. The value of nr_running() (which is the current number of runnable threads) is averaged over X samples by a ringbuffer. If the value is over a dynamically calculated value, all CPUs are onlined. When the value falls under another dynamically calculated value, the CPUs are offlined with a 2 second delay."

This reverts commit d2c74676463b1a5b6f9b0c77368b3e8eca321cc1.