x86: Use kick_all_cpus_sync()

Use kick_all_cpus_sync() and remove cpu_idle_wait().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120507175652.190382227@linutronix.de
Cc: x86@kernel.org