x86, acpi, idle: Restructure the mwait idle routines

People seem to delight in writing wrong and broken mwait idle routines;
collapse the lot.

This leaves mwait_play_dead() the sole remaining user of __mwait() and
new __mwait() users are probably doing it wrong.

Also remove __sti_mwait() as its unused.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jacob Jun Pan <jacob.jun.pan@linux.intel.com>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Len Brown <lenb@kernel.org>
Cc: Rui Zhang <rui.zhang@intel.com>
Acked-by: Rafael Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131212141654.616820819@infradead.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
index fc6008f..509452a 100644
--- a/drivers/acpi/acpi_pad.c
+++ b/drivers/acpi/acpi_pad.c
@@ -193,10 +193,7 @@
 					CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 			stop_critical_timings();
 
-			__monitor((void *)&current_thread_info()->flags, 0, 0);
-			smp_mb();
-			if (!need_resched())
-				__mwait(power_saving_mwait_eax, 1);
+			mwait_idle_with_hints(power_saving_mwait_eax, 1);
 
 			start_critical_timings();
 			if (lapic_marked_unstable)