USB: Serial: ch341.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: Rusty Russell <rusty@rustcorp.com.au>
CC: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/ch341.c

@@ -70,8 +70,6 @@
 #define CH341_NBREAK_BITS_REG2 0x40
 
 
-static bool debug;
-
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x4348, 0x5523) },
 	{ USB_DEVICE(0x1a86, 0x7523) },
@@ -621,6 +619,3 @@ static struct usb_serial_driver * const serial_drivers[] = {
 module_usb_serial_driver(serial_drivers, id_table);
 
 MODULE_LICENSE("GPL");
-
-module_param(debug, bool, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(debug, "Debug enabled or not");