USB: Serial: usb-serial: 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.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 47e2280..2966121 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -24,8 +24,6 @@
 #include <linux/kfifo.h>
 #include <linux/serial.h>
 
-static int debug;
-
 #ifdef CONFIG_USB_SERIAL_GENERIC
 
 static __u16 vendor  = 0x05f9;
@@ -60,11 +58,10 @@
 
 #endif
 
-int usb_serial_generic_register(int _debug)
+int usb_serial_generic_register(void)
 {
 	int retval = 0;
 
-	debug = _debug;
 #ifdef CONFIG_USB_SERIAL_GENERIC
 	generic_device_ids[0].idVendor = vendor;
 	generic_device_ids[0].idProduct = product;