ACPI: Add stubs for (un)register_acpi_bus_type

It's unreasonable to have CONFIG_ACPI for these in drivers, so add some
stub functions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 29a4a5c..1564e09 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -69,6 +69,7 @@
 	up_read(&bus_type_sem);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(register_acpi_bus_type);
 
 static int acpi_find_bridge_device(struct device *dev, acpi_handle * handle)
 {
@@ -85,6 +86,7 @@
 	up_read(&bus_type_sem);
 	return ret;
 }
+EXPORT_SYMBOL_GPL(unregister_acpi_bus_type);
 
 /* Get device's handler per its address under its parent */
 struct acpi_find_child {
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index f1c8ca6..c909984 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -407,6 +407,11 @@
 }
 #endif
 
+#else	/* CONFIG_ACPI */
+
+static int register_acpi_bus_type(struct acpi_bus_type *bus) { return 0; }
+static int unregister_acpi_bus_type(struct acpi_bus_type *bus) { return 0; }
+
 #endif				/* CONFIG_ACPI */
 
 #endif /*__ACPI_BUS_H__*/