ACPI / dock: Do not check CONFIG_ACPI_DOCK_MODULE

Since commit 94add0f (ACPI / dock: Initialize ACPI dock subsystem
upfront) the ACPI dock driver cannot be a module, so
CONFIG_ACPI_DOCK_MODULE is never set.  For this reason, simplify
the preprocessor conditional in include/acpi/acpi_drivers.h
referring to that sybbol unnecessarily.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/acpi/acpi_drivers.h

@@ -117,7 +117,7 @@ struct acpi_dock_ops {
 	acpi_notify_handler uevent;
 };
 
-#if defined(CONFIG_ACPI_DOCK) || defined(CONFIG_ACPI_DOCK_MODULE)
+#ifdef CONFIG_ACPI_DOCK
 extern int is_dock_device(acpi_handle handle);
 extern int register_dock_notifier(struct notifier_block *nb);
 extern void unregister_dock_notifier(struct notifier_block *nb);
@@ -150,6 +150,6 @@ static inline int register_hotplug_dock_device(acpi_handle handle,
 static inline void unregister_hotplug_dock_device(acpi_handle handle)
 {
 }
-#endif
+#endif /* CONFIG_ACPI_DOCK */
 
 #endif /*__ACPI_DRIVERS_H__*/