powerpc: Move definitions of secondary CPU spinloop to header file

Those definitions are currently declared extern in the .c file where
they are used, move them to a header file instead.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/smp.h

@@ -148,6 +148,15 @@ extern struct smp_ops_t *smp_ops;
 extern void arch_send_call_function_single_ipi(int cpu);
 extern void arch_send_call_function_ipi(cpumask_t mask);
 
+/* Definitions relative to the secondary CPU spin loop
+ * and entry point. Not all of them exist on both 32 and
+ * 64-bit but defining them all here doesn't harm
+ */
+extern void generic_secondary_smp_init(void);
+extern unsigned long __secondary_hold_spinloop;
+extern unsigned long __secondary_hold_acknowledge;
+extern char __secondary_hold;
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __KERNEL__ */

arch/powerpc/kernel/prom_init.c

@@ -1259,10 +1259,6 @@ static void __init prom_initialize_tce_table(void)
  *
  * -- Cort
  */
-extern char __secondary_hold;
-extern unsigned long __secondary_hold_spinloop;
-extern unsigned long __secondary_hold_acknowledge;
-
 /*
  * We want to reference the copy of __secondary_hold_* in the
  * 0 - 0x100 address range

arch/powerpc/kernel/setup_64.c

@@ -230,9 +230,6 @@ void early_setup_secondary(void)
 #endif /* CONFIG_SMP */
 
 #if defined(CONFIG_SMP) || defined(CONFIG_KEXEC)
-extern unsigned long __secondary_hold_spinloop;
-extern void generic_secondary_smp_init(void);
-
 void smp_release_cpus(void)
 {
 	unsigned long *ptr;

arch/powerpc/platforms/85xx/smp.c

@@ -25,7 +25,6 @@
 
 #include <sysdev/fsl_soc.h>
 
-extern volatile unsigned long __secondary_hold_acknowledge;
 extern void __early_start(void);
 
 #define BOOT_ENTRY_ADDR_UPPER	0

arch/powerpc/platforms/86xx/mpc86xx_smp.c

@@ -27,7 +27,6 @@
 #include "mpc86xx.h"
 
 extern void __secondary_start_mpc86xx(void);
-extern unsigned long __secondary_hold_acknowledge;
 
 #define MCM_PORT_CONFIG_OFFSET	0x10
 

arch/powerpc/platforms/cell/smp.c

@@ -58,8 +58,6 @@
  */
 static cpumask_t of_spin_map;
 
-extern void generic_secondary_smp_init(unsigned long);
-
 /**
  * smp_startup_cpu() - start the given cpu
  *

arch/powerpc/platforms/pseries/smp.c

@@ -56,8 +56,6 @@
  */
 static cpumask_t of_spin_map;
 
-extern void generic_secondary_smp_init(unsigned long);
-
 /**
  * smp_startup_cpu() - start the given cpu
  *