firewire: consistent ifndef blocks in header files

Replace __fw_core_h by __fw_transaction_h to match the file name.
Add comments to the final #endif in header files.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 84cd5e7..731abbe 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -124,4 +124,4 @@
 
 extern struct file_operations fw_device_ops;
 
-#endif
+#endif /* __fw_device_h */