USB: Serial: pl2303.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: Johan Hovold <jhovold@gmail.com>
CC: Alan Stern <stern@rowland.harvard.edu>
CC: Wang YanQing <Udknight@gmail.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/pl2303.c

@@ -36,8 +36,6 @@
  */
 #define DRIVER_DESC "Prolific PL2303 USB to serial adaptor driver"
 
-static bool debug;
-
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID) },
 	{ USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ2) },
@@ -839,7 +837,3 @@ module_usb_serial_driver(serial_drivers, id_table);
 
 MODULE_DESCRIPTION(DRIVER_DESC);
 MODULE_LICENSE("GPL");
-
-module_param(debug, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(debug, "Debug enabled or not");
-