tools/memory-model: Fix reference to litmus test in recipes.txt

The name of litmus test doesn't match the one described below.
Fix the name of litmus test.

Acked-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>