Revert "rcu:reduce__call_rcu()-induced contention on rcu_node structures"

This reverts commit 331070e00b25cd17bb886ffc1417adb438ca4cff.
Revert "rcu: Make synchronize_srcu_expedited() fast if running readers"

This reverts commit 57a640f83079796bf490445f897342df286d67a9.