Revert "Fix lockup related to stop_machine being stuck in __do_softirq."

This reverts commit 0f67ff9b4e993bfac78180f99cd89b4ea0446bae.
Revert "softirq: reduce latencies"

This reverts commit 2315e7e75fa1393305ac058e6909fd54afef8e16.
Revert "irq: Set CPU affinity right on thread creation"

This reverts commit 37071c343ab43c1f907bd9a67280b013478e885a.