Temove the mistaken turning on of NO_IDLE_HZ on x86+PARAVIRT kernels.

It's an obsolete, limited form of dynticks.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>