ACPI / sleep: Make acpi_sleep_syscore_init() static

Function acpi_sleep_syscore_init has no external user so it should be
static.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sleep.c

@@ -870,7 +870,7 @@ static struct syscore_ops acpi_sleep_syscore_ops = {
 	.resume = acpi_restore_bm_rld,
 };
 
-void acpi_sleep_syscore_init(void)
+static void acpi_sleep_syscore_init(void)
 {
 	register_syscore_ops(&acpi_sleep_syscore_ops);
 }