USB: fix up license wording on some of my usb-serial drivers

Also update the copyright date on the pl2303 driver, as it was out of date.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/omninet.c b/drivers/usb/serial/omninet.c
index 00afc17..48094d1 100644
--- a/drivers/usb/serial/omninet.c
+++ b/drivers/usb/serial/omninet.c
@@ -1,10 +1,9 @@
 /*
  * USB ZyXEL omni.net LCD PLUS driver
  *
- *	This program is free software; you can redistribute it and/or modify
- *	it under the terms of the GNU General Public License as published by
- *	the Free Software Foundation; either version 2 of the License, or
- *	(at your option) any later version.
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License version
+ *	2 as published by the Free Software Foundation.
  *
  * See Documentation/usb/usb-serial.txt for more information on using this driver
  *