rcu: Update tree_exp.h function-header comments

The function-header comments in kernel/rcu/tree_exp.h have gotten a bit
out of date, so this commit updates a number of them.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2019-11-27 14:20:41 -08:00
commit de8cd0a533