ACPI / cpuidle: Remove acpi_idle_suspend (to fix suspend regression)

After commit e978aa7d7d57 ("cpuidle: Move dev->last_residency update to
driver enter routine; remove dev->last_state") setting acpi_idle_suspend
to 1 by acpi_processor_suspend() causes the ACPI cpuidle routines to
return error codes continuously, which in turn causes cpuidle to lock up
(hard).

However, acpi_idle_suspend doesn't appear to be useful for any
particular purpose (it's racy and doesn't really provide any real
protection), so it can be removed, which makes the problem go away.

Reported-and-tested-by: Tomas M. <[e-mail]>
Reported-and-tested-by: Ferenc Wagner <[e-mail]>
Tested-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/acpi/processor_idle.c

···
 /*
  * Suspend / resume control
  */
-static int acpi_idle_suspend;
 static u32 saved_bm_rld;
 
 static void acpi_idle_bm_rld_save(void)
···
 
 int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
 {
-	if (acpi_idle_suspend == 1)
-		return 0;
-
 	acpi_idle_bm_rld_save();
-	acpi_idle_suspend = 1;
 	return 0;
 }
 
 int acpi_processor_resume(struct acpi_device * device)
 {
-	if (acpi_idle_suspend == 0)
-		return 0;
-
 	acpi_idle_bm_rld_restore();
-	acpi_idle_suspend = 0;
 	return 0;
 }
 
···
 
 	local_irq_disable();
 
-	/* Do not access any ACPI IO ports in suspend path */
-	if (acpi_idle_suspend) {
-		local_irq_enable();
-		cpu_relax();
-		return -EINVAL;
-	}
-
 	lapic_timer_state_broadcast(pr, cx, 1);
 	kt1 = ktime_get_real();
 	acpi_idle_do_entry(cx);
···
 		return -EINVAL;
 
 	local_irq_disable();
-
-	if (acpi_idle_suspend) {
-		local_irq_enable();
-		cpu_relax();
-		return -EINVAL;
-	}
-
 
 	if (cx->entry_method != ACPI_CSTATE_FFH) {
 		current_thread_info()->status &= ~TS_POLLING;
···
 
 	if (unlikely(!pr))
 		return -EINVAL;
-
-
-	if (acpi_idle_suspend) {
-		cpu_relax();
-		return -EINVAL;
-	}
 
 	if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
 		if (drv->safe_state_index >= 0) {