rcu: Remove stale comment in tree.c
rcu: Remove stale comment in tree.c

This commit removes a stale comment in rcu/tree.c which was left
out when some code was moved around previously in commit 2036d94a7b61
("rcu:  Rework detection of use of RCU by offline CPUs") For reference,
the following updated comment exists a few lines below this which means
the same:

/* Remove the outgoing CPU from the masks in the rcu_node hierarchy. */

Signed-off-by: Pranith Kumar <99f39d96f0d0b011d351b608fe7e2870596fa4a9@gmail.com>
Reviewed-by: Josh Triplett <c028c213ed5efcf30c3f4fc7361dbde0c893c5b7@joshtriplett.org>
Reviewed-by: Lai Jiangshan <4c9eb49378914b743bdd32292c04df29b820d73e@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <1e0ce936bb9b355d257bf5790d2513c3f28be22b@linux.vnet.ibm.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs