cpuidle: Remove unnecessary wrapper cpuidle_get_last_residency()

cpuidle_get_last_residency() is just a wrapper for retrieving
the last_residency member of struct cpuidle_device.  It's also
weirdly the only wrapper function for accessing cpuidle_* struct
member (by my best guess is it could be a leftover from v2.x).

Anyhow, since the only two users (the ladder and menu governors)
can access dev->last_residency directly, and it's more intuitive to
do it that way, let's just get rid of the wrapper.

This patch tidies up CPU idle code a bit without functional changes.
Signed-off-by: NFieah Lim <kw@fieahl.im>
[ rjw: Changelog cleanup ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/governors/ladder.c

@@ -80,7 +80,7 @@ static int ladder_select_state(struct cpuidle_driver *drv,
 
 	last_state = &ldev->states[last_idx];
 
-	last_residency = cpuidle_get_last_residency(dev) - drv->states[last_idx].exit_latency;
+	last_residency = dev->last_residency - drv->states[last_idx].exit_latency;
 
 	/* consider promotion */
 	if (last_idx < drv->state_count - 1 &&

drivers/cpuidle/governors/menu.c

@@ -514,7 +514,7 @@ static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 		measured_us = 9 * MAX_INTERESTING / 10;
 	} else {
 		/* measured value */
-		measured_us = cpuidle_get_last_residency(dev);
+		measured_us = dev->last_residency;
 
 		/* Deduct exit latency */
 		if (measured_us > 2 * target->exit_latency)

include/linux/cpuidle.h

@@ -99,16 +99,6 @@ struct cpuidle_device {
 DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);
 DECLARE_PER_CPU(struct cpuidle_device, cpuidle_dev);
 
-/**
- * cpuidle_get_last_residency - retrieves the last state's residency time
- * @dev: the target CPU
- */
-static inline int cpuidle_get_last_residency(struct cpuidle_device *dev)
-{
-	return dev->last_residency;
-}
-
-
 /****************************
  * CPUIDLE DRIVER INTERFACE *
  ****************************/