rcutorture: Drop sparse lock-acquisition annotations

The sparse __acquires() and __releases() annotations provide very
little value.  The argument is ignored, so sparse cannot tell the
differences between acquiring one lock and releasing another on the one
hand and acquiring and releasing a given lock on the other.  In addition,
lockdep annotations provide much more precision, for but one example,
actually knowing which lock is held.

This commit therefore removes the __acquires() and __releases()
annotations from rcutorture.

Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>