USB: Serial: sierra.c: remove debug module parameter

Now that all usb-serial modules are only using dev_dbg()
the debug module parameter does not do anything at all, so
remove it to reduce any confusion if someone were to try to
use it.

CC: Alan Stern <stern@rowland.harvard.edu>
CC: "Bjørn Mork" <bjorn@mork.no>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/sierra.c

@@ -46,7 +46,6 @@
    allocations > PAGE_SIZE and the number of packets in a page
    is an integer 512 is the largest possible packet on EHCI */
 
-static bool debug;
 static bool nmea;
 
 /* Used in interface blacklisting */
@@ -765,7 +764,6 @@ static struct urb *sierra_setup_urb(struct usb_serial *serial, int endpoint,
 			usb_sndbulkpipe(serial->dev, endpoint) | dir,
 			buf, len, callback, ctx);
 
-		/* debug */
 		dev_dbg(&serial->dev->dev, "%s %c u : %p d:%p\n", __func__,
 				dir == USB_DIR_IN ? 'i' : 'o', urb, buf);
 	} else {
@@ -1082,6 +1080,3 @@ MODULE_LICENSE("GPL");
 
 module_param(nmea, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(nmea, "NMEA streaming");
-
-module_param(debug, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(debug, "Debug messages");