tty: amiserial: fix invalid user-pointer check

Drop invalid user-pointer check from TIOCGSERIAL handler.

A NULL-pointer can be valid in user space and copy_to_user() takes care
of sanity checking.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/amiserial.c

@@ -1012,8 +1012,6 @@ static int get_serial_info(struct tty_struct *tty, struct serial_state *state,
 {
 	struct serial_struct tmp;
    
-	if (!retinfo)
-		return -EFAULT;
 	memset(&tmp, 0, sizeof(tmp));
 	tty_lock(tty);
 	tmp.line = tty->index;