(DO NOT MERGE) Revert "ARM: 9095/1: ARM64: Remove arm_pm_restart()"

This reverts commit ab6cef1.

Temporary fix to compile error:
  /srv/source/drivers/power/reset/odroid-reboot.c: In function ‘odroid_restart_probe’:
  /srv/source/drivers/power/reset/odroid-reboot.c:141:3: error: ‘arm_pm_restart’
  undeclared (first use in this function); did you mean ‘alarm_restart’?
    141 |   arm_pm_restart = do_odroid_restart;
        |   ^~~~~~~~~~~~~~
        |   alarm_restart
  /srv/source/drivers/power/reset/odroid-reboot.c:141:3: note: each
  undeclared identifier is reported only once for each function it appears in

commit: 59541fb "ODROID-COMMON: power:reset: Add odroid support"

Change-Id: Id81d2cb4c7a55e660e7158a8eb7937fff077abcf

arch/arm64/include/asm/system_misc.h

@@ -32,6 +32,8 @@ void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
 struct mm_struct;
 extern void __show_regs(struct pt_regs *);
 
+extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
+
 #endif	/* __ASSEMBLY__ */
 
 #endif	/* __ASM_SYSTEM_MISC_H */

arch/arm64/kernel/process.c

@@ -70,6 +70,8 @@ EXPORT_SYMBOL(__stack_chk_guard);
 void (*pm_power_off)(void);
 EXPORT_SYMBOL_GPL(pm_power_off);
 
+void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
+
 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)
 {
@@ -140,7 +142,10 @@ void machine_restart(char *cmd)
 		efi_reboot(reboot_mode, NULL);
 
 	/* Now call the architecture specific reboot code. */
-	do_kernel_restart(cmd);
+	if (arm_pm_restart)
+		arm_pm_restart(reboot_mode, cmd);
+	else
+		do_kernel_restart(cmd);
 
 	/*
 	 * Whoops - the architecture was unable to reboot.