arm,arm64,drivers: move externs in a new header file

Create a new header file (include/linux/arch_topology.h) and put there
declarations of interfaces used by arm, arm64 and drivers code.
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm/kernel/topology.c

@@ -11,6 +11,7 @@
  * for more details.
  */
 
+#include <linux/arch_topology.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/cpumask.h>
@@ -45,10 +46,6 @@
  * updated during this sequence.
  */
 
-extern unsigned long
-arch_scale_cpu_capacity(struct sched_domain *sd, int cpu);
-extern void set_capacity_scale(unsigned int cpu, unsigned long capacity);
-
 #ifdef CONFIG_OF
 struct cpu_efficiency {
 	const char *compatible;
@@ -76,8 +73,6 @@ static unsigned long *__cpu_capacity;
 
 static unsigned long middle_capacity = 1;
 static bool cap_from_dt = true;
-extern void normalize_cpu_capacity(void);
-extern int __init parse_cpu_capacity(struct device_node *cpu_node, int cpu);
 
 /*
  * Iterate all CPUs' descriptor in DT and compute the efficiency

arch/arm64/kernel/topology.c

@@ -11,6 +11,7 @@
  * for more details.
  */
 
+#include <linux/arch_topology.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/init.h>
@@ -27,9 +28,6 @@
 #include <asm/cputype.h>
 #include <asm/topology.h>
 
-extern void normalize_cpu_capacity(void);
-extern int __init parse_cpu_capacity(struct device_node *cpu_node, int cpu);
-
 static int __init get_cpu_for_node(struct device_node *node)
 {
 	struct device_node *cpu_node;

drivers/base/arch_topology.c

@@ -13,6 +13,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/arch_topology.h>
 #include <linux/cpu.h>
 #include <linux/cpufreq.h>
 #include <linux/device.h>

include/linux/arch_topology.h

+/*
+ * include/linux/arch_topology.h - arch specific cpu topology information
+ */
+#ifndef _LINUX_ARCH_TOPOLOGY_H_
+#define _LINUX_ARCH_TOPOLOGY_H_
+
+void normalize_cpu_capacity(void);
+
+struct device_node;
+int parse_cpu_capacity(struct device_node *cpu_node, int cpu);
+
+struct sched_domain;
+unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu);
+
+void set_capacity_scale(unsigned int cpu, unsigned long capacity);
+
+#endif /* _LINUX_ARCH_TOPOLOGY_H_ */