staging: dgap: remove redundant error value check

The retval in dgap_block_til_ready() is initialized to zero,
and if no error has occurred in this function, the retval has a zero.
So it doesn't need to check "retval" itself.
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgap/dgap.c

@@ -2181,10 +2181,7 @@ static int dgap_block_til_ready(struct tty_struct *tty, struct file *file,
 
 	spin_unlock_irqrestore(&ch->ch_lock, lock_flags);
 
-	if (retval)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 /*