USB: serial: mos7840: drop serial struct accessor

Drop the helper used to retrieve the serial struct pointer from the port
structure.

Note that this helper was only used when the serial structure was
actually not needed.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/mos7840.c

@@ -446,19 +446,6 @@ static void mos7840_led_activity(struct usb_serial_port *port)
 				jiffies + msecs_to_jiffies(LED_ON_MS));
 }
 
-static struct usb_serial *mos7840_get_usb_serial(struct usb_serial_port *port,
-						 const char *function)
-{
-	/* if no port was specified */
-	if (!port) {
-		/* then say that we don't have a valid usb_serial thing,
-		 * which will end up genrating -ENODEV return values */
-		return NULL;
-	}
-
-	return port->serial;
-}
-
 /*****************************************************************************
  * mos7840_bulk_in_callback
  *	this is the callback function for when we have received data on the
@@ -471,7 +458,6 @@ static void mos7840_bulk_in_callback(struct urb *urb)
 	struct usb_serial_port *port = mos7840_port->port;
 	int retval;
 	unsigned char *data;
-	struct usb_serial *serial;
 	int status = urb->status;
 
 	if (status) {
@@ -480,12 +466,6 @@ static void mos7840_bulk_in_callback(struct urb *urb)
 		return;
 	}
 
-	serial = mos7840_get_usb_serial(port, __func__);
-	if (!serial) {
-		mos7840_port->read_urb_busy = false;
-		return;
-	}
-
 	data = urb->transfer_buffer;
 	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
 
@@ -822,15 +802,10 @@ static int mos7840_chars_in_buffer(struct tty_struct *tty)
 
 static void mos7840_close(struct usb_serial_port *port)
 {
-	struct usb_serial *serial;
 	struct moschip_port *mos7840_port;
 	int j;
 	__u16 Data;
 
-	serial = mos7840_get_usb_serial(port, __func__);
-	if (!serial)
-		return;
-
 	mos7840_port = mos7840_get_port_private(port);
 	if (mos7840_port == NULL)
 		return;
@@ -866,13 +841,8 @@ static void mos7840_break(struct tty_struct *tty, int break_state)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	unsigned char data;
-	struct usb_serial *serial;
 	struct moschip_port *mos7840_port;
 
-	serial = mos7840_get_usb_serial(port, __func__);
-	if (!serial)
-		return;
-
 	mos7840_port = mos7840_get_port_private(port);
 
 	if (mos7840_port == NULL)