ACPI, intel_idle: Cleanup idle= internal variables

Having four variables for the same thing:
  idle_halt, idle_nomwait, force_mwait and boot_option_idle_overrides
is rather confusing and unnecessary complex.

if idle= boot param is passed, only set up one variable:
boot_option_idle_overrides

Introduces following functional changes/fixes:
  - intel_idle driver does not register if any idle=xy
    boot param is passed.
  - processor_idle.c will also not register a cpuidle driver
    and get active if idle=halt is passed.
    Before a cpuidle driver with one (C1, halt) state got registered
    Now the default_idle function will be used which finally uses
    the same idle call to enter sleep state (safe_halt()), but
    without registering a whole cpuidle driver.

That means idle= param will always avoid cpuidle drivers to register
with one exception (same behavior as before):
idle=nomwait
may still register acpi_idle cpuidle driver, but C1 will not use
mwait, but hlt. This can be a workaround for IO based deeper sleep
states where C1 mwait causes problems.

Signed-off-by: Thomas Renninger <trenn@suse.de>
cc: x86@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>

arch/ia64/kernel/process.c

@@ -53,12 +53,8 @@
 
 void (*ia64_mark_idle)(int);
 
-unsigned long boot_option_idle_override = 0;
+unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
 EXPORT_SYMBOL(boot_option_idle_override);
-unsigned long idle_halt;
-EXPORT_SYMBOL(idle_halt);
-unsigned long idle_nomwait;
-EXPORT_SYMBOL(idle_nomwait);
 void (*pm_idle) (void);
 EXPORT_SYMBOL(pm_idle);
 void (*pm_power_off) (void);