UPSTREAM: rcu/kvfree: Remove useless monitor_todo flag

monitor_todo is not needed as the work struct already tracks
if work is pending. Just use that to know if work is pending
using schedule_delayed_work() helper.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
(cherry picked from commit 82d26c36)

Bug: 258241771
Bug: 222463781
Test: CQ
Change-Id: I4c13f89da735a628a5030ab55a13e338b97da4b8
Signed-off-by: Joel Fernandes <joelaf@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4332176


Reviewed-by: Sean Paul <sean@poorly.run>
Reviewed-by: Vineeth Pillai <vineethrp@google.com>
(cherry picked from commit bb867be28d6a70b36ff1d6563f794c489072ab7e)
[Minor conflict with 71cf9c98 where it
added a new function in the same location.
Cherry picked from chromeos-5.15 tree. Minor tweaks to commit message
to match Android style]
Signed-off-by: Qais Yousef <qyousef@google.com>