usb: s3c-otg: Tweak the comments

The driver is actually for the Designware DWC2 controller.
Tweak the comments in the driver to reflect this fact.

Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/include/usb/s3c_udc.h b/include/usb/s3c_udc.h
index 20af629..497248d 100644
--- a/include/usb/s3c_udc.h
+++ b/include/usb/s3c_udc.h
@@ -1,6 +1,6 @@
 /*
  * drivers/usb/gadget/s3c_udc.h
- * Samsung S3C on-chip full/high speed USB device controllers
+ * Designware DWC2 on-chip full/high speed USB device controllers
  * Copyright (C) 2005 for Samsung Electronics
  *
  * SPDX-License-Identifier:	GPL-2.0+