ACPI: debug: Make two functions static

Fix sparse warnings:

drivers/acpi/acpi_dbg.c:748:12: warning:
 symbol 'acpi_aml_init' was not declared. Should it be static?
drivers/acpi/acpi_dbg.c:774:13: warning:
 symbol 'acpi_aml_exit' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_dbg.c

@@ -745,7 +745,7 @@ static const struct acpi_debugger_ops acpi_aml_debugger = {
 	.notify_command_complete = acpi_aml_notify_command_complete,
 };
 
-int __init acpi_aml_init(void)
+static int __init acpi_aml_init(void)
 {
 	int ret;
 
@@ -771,7 +771,7 @@ int __init acpi_aml_init(void)
 	return 0;
 }
 
-void __exit acpi_aml_exit(void)
+static void __exit acpi_aml_exit(void)
 {
 	if (acpi_aml_initialized) {
 		acpi_unregister_debugger(&acpi_aml_debugger);