[PATCH] tty: fix badzero.cocci warnings

[kbuild test robot]

drivers/tty/tty_io.c:731:36-37: WARNING comparing pointer to 0

 Compare pointer-typed values to NULL rather than 0

Semantic patch information:
 This makes an effort to choose between !x and x == NULL.  !x is used
 if it has previously been used with the function used to initialize x.
 This relies on type information.  More type information can be obtained
 using the option -all_includes and the option -I to specify an
 include path.

Generated by: scripts/coccinelle/null/badzero.cocci

CC: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
---

 tty_io.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -728,7 +728,7 @@ static void __tty_hangup(struct tty_stru
 	while (refs--)
 		tty_kref_put(tty);
 
-	tty_ldisc_hangup(tty, cons_filp != 0);
+	tty_ldisc_hangup(tty, cons_filp != NULL);
 
 	spin_lock_irq(&tty->ctrl_lock);
 	clear_bit(TTY_THROTTLED, &tty->flags);