rcutorture: Add CONFIG_PREEMPT_DYNAMIC=n to tiny scenarios

With CONFIG_PREEMPT_DYNAMIC=y, the kernel builds with CONFIG_PREEMPTION=y
because preemption can be enabled at runtime.  This prevents any tests
of Tiny RCU or Tiny SRCU from running correctly.  This commit therefore
explicitly sets CONFIG_PREEMPT_DYNAMIC=n for those scenarios.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>