MAINTAINERS: Change Joel Fernandes from R: to M:

I have spent years learning / contributing to RCU with several features,
talks and presentations, with my most recent work being on Lazy-RCU.

Please consider me for M, so I can tell my wife why I spend a lot of my
weekends and evenings on this complicated and mysterious thing -- which is
mostly in the hopes of preventing the world from burning down because
everything runs on this one way or another. ;-)

Acked-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>