cpuidle: haltpoll: Take 'idle=' override into account

Currenly haltpoll isn't aware of the 'idle=' override, the priority is
'idle=poll' > haltpoll > 'idle=halt'. When 'idle=poll' is used, cpuidle
driver is bypassed but current_driver in sys still shows 'haltpoll'.

When 'idle=halt' is used, haltpoll takes precedence and makes
'idle=halt' have no effect.

Add a check to prevent the haltpoll driver from loading if 'idle=' is
present.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle-haltpoll.c

@@ -95,6 +95,10 @@ static int __init haltpoll_init(void)
 	int ret;
 	struct cpuidle_driver *drv = &haltpoll_driver;
 
+	/* Do not load haltpoll if idle= is passed */
+	if (boot_option_idle_override != IDLE_NO_OVERRIDE)
+		return -ENODEV;
+
 	cpuidle_poll_state_init(drv);
 
 	if (!kvm_para_available() ||