Revert RCU Commits

Revert "rcu: Add RCU_FAST_NO_HZ tracing for idle exit"

This reverts commit 737d75a1ff4d7d239a97daefe40e73b7b1050571.
Revert "rcu: Make RCU_FAST_NO_HZ use timer rather than hrtimer"

This reverts commit 5dc9624a6ac5a336b879a709325b802a116f9279.
Revert "rcu: Make RCU_FAST_NO_HZ account for pauses out of idle"

This reverts commit 3e5f39836de3e7211f65b79b5acf353a9951a860.
Revert "rcu: Add warning for RCU_FAST_NO_HZ timer firing"

This reverts commit 1b00f5d0dc9b639445f21052f23b784c465a4365.
Revert "rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU"

This reverts commit 92b5560fb3eba94a575bb08ffabb4d7da074c758.
Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation"

This reverts commit bcf69e0cbe4a9008eeb3825866e5429001a4f8fe.
Revert "rcu: Make exit_rcu() more precise and consolidate"

This reverts commit 85416aef1a88156585a7ce26cdc4440ff5834982.
Revert "rcu: Make RCU_FAST_NO_HZ handle timer migration"

This reverts commit 0bd8cf3ef880cd060d3d220cadca4e5c366dec7b.
Revert "rcu: Explicitly initialize RCU_FAST_NO_HZ per-CPU variables"

This reverts commit 96bca7b5690c003447f9206408dfa0b1a51adb26.
Revert "rcu: Make rcu_barrier() less disruptive"

This reverts commit 41c94a17fe66c5f4f99adeb6fcdc2a0595293942.
Revert "timer: Fix mod_timer_pinned() header comment"

This reverts commit bc258657e8ce3b87c740f70f560a2aa1a593c517.
Revert "rcu: Update RCU_FAST_NO_HZ tracing for lazy callbacks"

This reverts commit 5ba0eeedf56bfca825561298517172f9340c590e.
Revert "rcu: Move RCU_FAST_NO_HZ per-CPU variables to rcu_dynticks structure"

This reverts commit 13653f312444170103baf5d974a58e81ff1fd1ac.
Revert "rcu: Precompute RCU_FAST_NO_HZ timer offsets"

This reverts commit b9b622b53c120ef0bd6cfedfc09ed332cc21a8cd.
Revert "Revert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation""

This reverts commit b1426af3dd97daf6ced7e16f2773b0037003ea06.
Revert "rcu: Stop rcu_do_batch() from multiplexing the "count" variable"

This reverts commit ec680073a8a01536e066241b1186534812f6c13f.