cpufreq: CPPC: Remove forward declaration of cppc_cpufreq_register_em()

cppc_cpufreq_register_em() is only used in populate_efficiency_class(). A
forward declaration of it is not necessary.

Move cppc_cpufreq_register_em() in front of populate_efficiency_class()
and remove the forward declaration of cppc_cpufreq_register_em().

No functional change.

Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Link: https://patch.msgid.link/20250526113057.3086513-4-zhenglifeng1@huawei.com
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: Lifeng Zheng

drivers/cpufreq/cppc_cpufreq.c

@@ -344,7 +344,6 @@ static unsigned int cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
 #if defined(CONFIG_ARM64) && defined(CONFIG_ENERGY_MODEL)
 
 static DEFINE_PER_CPU(unsigned int, efficiency_class);
-static void cppc_cpufreq_register_em(struct cpufreq_policy *policy);
 
 /* Create an artificial performance state every CPPC_EM_CAP_STEP capacity unit. */
 #define CPPC_EM_CAP_STEP	(20)
@@ -480,6 +479,18 @@ static int cppc_get_cpu_cost(struct device *cpu_dev, unsigned long KHz,
 	return 0;
 }
 
+static void cppc_cpufreq_register_em(struct cpufreq_policy *policy)
+{
+	struct cppc_cpudata *cpu_data;
+	struct em_data_callback em_cb =
+		EM_ADV_DATA_CB(cppc_get_cpu_power, cppc_get_cpu_cost);
+
+	cpu_data = policy->driver_data;
+	em_dev_register_perf_domain(get_cpu_device(policy->cpu),
+			get_perf_level_count(policy), &em_cb,
+			cpu_data->shared_cpu_map, 0);
+}
+
 static void populate_efficiency_class(void)
 {
 	struct acpi_madt_generic_interrupt *gicc;
@@ -514,18 +525,6 @@ static void populate_efficiency_class(void)
 	cppc_cpufreq_driver.register_em = cppc_cpufreq_register_em;
 }
 
-static void cppc_cpufreq_register_em(struct cpufreq_policy *policy)
-{
-	struct cppc_cpudata *cpu_data;
-	struct em_data_callback em_cb =
-		EM_ADV_DATA_CB(cppc_get_cpu_power, cppc_get_cpu_cost);
-
-	cpu_data = policy->driver_data;
-	em_dev_register_perf_domain(get_cpu_device(policy->cpu),
-			get_perf_level_count(policy), &em_cb,
-			cpu_data->shared_cpu_map, 0);
-}
-
 #else
 static void populate_efficiency_class(void)
 {