USB: legousbtower: drop redundant NULL check

Drop redundant NULL check from tower_abort_transfers(), which is never
called with a NULL argument.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191105084152.16322-3-johan@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/misc/legousbtower.c

@@ -457,9 +457,6 @@ static int tower_release (struct inode *inode, struct file *file)
  */
 static void tower_abort_transfers (struct lego_usb_tower *dev)
 {
-	if (dev == NULL)
-		return;
-
 	/* shutdown transfer */
 	if (dev->interrupt_in_running) {
 		dev->interrupt_in_running = 0;