ARM: cpuidle: constify return value of arm_cpuidle_get_ops()

arm_cpuidle_read_ops() just copies '*ops' to cpuidle_ops[cpu], so the
structure '*ops' is not modified at all.

The comment is also updated accordingly.
Signed-off-by: NJisheng Zhang <jszhang@marvell.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

arch/arm/kernel/cpuidle.c

@@ -70,7 +70,7 @@ int arm_cpuidle_suspend(int index)
  *
  * Returns a struct cpuidle_ops pointer, NULL if not found.
  */
-static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
+static const struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
 {
 	struct of_cpuidle_method *m = __cpuidle_method_of_table;
 
@@ -88,7 +88,7 @@ static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
  *
  * Get the method name defined in the 'enable-method' property, retrieve the
  * associated cpuidle_ops and do a struct copy. This copy is needed because all
- * cpuidle_ops are tagged __initdata and will be unloaded after the init
+ * cpuidle_ops are tagged __initconst and will be unloaded after the init
  * process.
  *
  * Return 0 on sucess, -ENOENT if no 'enable-method' is defined, -EOPNOTSUPP if
@@ -97,7 +97,7 @@ static struct cpuidle_ops *__init arm_cpuidle_get_ops(const char *method)
 static int __init arm_cpuidle_read_ops(struct device_node *dn, int cpu)
 {
 	const char *enable_method;
-	struct cpuidle_ops *ops;
+	const struct cpuidle_ops *ops;
 
 	enable_method = of_get_property(dn, "enable-method", NULL);
 	if (!enable_method)