Documentation: Rename rcu_node_context_switch() to rcu_note_context_switch()

While Paul was explaining some RCU magic I noticed a typo in
rcu_note_context_switch().  As a result, this commit replaces
rcu_node_context_switch() with rcu_note_context_switch().

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>

Author: Sebastian Andrzej Siewior

Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst

@@ -423,7 +423,7 @@ wait on.
 +-----------------------------------------------------------------------+
 
 If the CPU does a context switch, a quiescent state will be noted by
-``rcu_node_context_switch()`` on the left. On the other hand, if the CPU
+``rcu_note_context_switch()`` on the left. On the other hand, if the CPU
 takes a scheduler-clock interrupt while executing in usermode, a
 quiescent state will be noted by ``rcu_sched_clock_irq()`` on the right.
 Either way, the passage through a quiescent state will be noted in a