rcutorture: Stop testing RCU Tasks Rude asynchronous APIs

The call_rcu_tasks_rude() and rcu_barrier_tasks_rude() APIs are currently
unused.  Furthermore, the idea is to get rid of RCU Tasks Rude entirely
once all architectures have their deep-idle and entry/exit code correctly
marked as inline or noinstr.  As a first step towards this goal, this
commit therefore removes these two functions from rcutorture testing.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>