cpuidle: ladder governor - use macro instead of hardcoded value

use CPUIDLE_DRIVER_STATE_START, instead of hardcoded value 0. As,
CPUIDLE_DRIVER_STATE_START can be 1/0 based on
CONFIG_ARCH_HAS_CPU_RELAX is defined or not.

Signed-off-by: Mohammad Merajul Islam Molla <meraj.enigma@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/governors/ladder.c

@@ -144,7 +144,7 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
 
 	ldev->last_state_idx = CPUIDLE_DRIVER_STATE_START;
 
-	for (i = 0; i < drv->state_count; i++) {
+	for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
 		state = &drv->states[i];
 		lstate = &ldev->states[i];
 
@@ -156,7 +156,7 @@ static int ladder_enable_device(struct cpuidle_driver *drv,
 
 		if (i < drv->state_count - 1)
 			lstate->threshold.promotion_time = state->exit_latency;
-		if (i > 0)
+		if (i > CPUIDLE_DRIVER_STATE_START)
 			lstate->threshold.demotion_time = state->exit_latency;
 	}