ACPI: Fix white space in a structure definition

Add a missing space in the definition of struct acpi_device_bus_id.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
[ rjw: Subject and changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/internal.h

@@ -88,7 +88,7 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent);
 
 extern struct list_head acpi_bus_id_list;
 
-struct acpi_device_bus_id{
+struct acpi_device_bus_id {
 	char bus_id[15];
 	unsigned int instance_no;
 	struct list_head node;