USB: serial: ftdi_sio: clean up ioctl handler

Clean up the ioctl handler and make sure to pass an unsigned-int rather
than serial_struct pointer to the TIOCSERGETLSR helper as this it what
the user argument really is.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/ftdi_sio.c

@@ -1534,7 +1534,7 @@ static int set_serial_info(struct tty_struct *tty,
 }
 
 static int get_lsr_info(struct usb_serial_port *port,
-			struct serial_struct __user *retinfo)
+			unsigned int __user *retinfo)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
 	unsigned int result = 0;
@@ -2485,20 +2485,15 @@ static int ftdi_ioctl(struct tty_struct *tty,
 					unsigned int cmd, unsigned long arg)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	void __user *argp = (void __user *)arg;
 
-	/* Based on code from acm.c and others */
 	switch (cmd) {
-
-	case TIOCGSERIAL: /* gets serial port data */
-		return get_serial_info(port,
-					(struct serial_struct __user *) arg);
-
-	case TIOCSSERIAL: /* sets serial port data */
-		return set_serial_info(tty, port,
-					(struct serial_struct __user *) arg);
+	case TIOCGSERIAL:
+		return get_serial_info(port, argp);
+	case TIOCSSERIAL:
+		return set_serial_info(tty, port, argp);
 	case TIOCSERGETLSR:
-		return get_lsr_info(port, (struct serial_struct __user *)arg);
-		break;
+		return get_lsr_info(port, argp);
 	default:
 		break;
 	}