TTY: pdc_cons, fix racy tty test

The tty->count test in the timer was racy. Let's remove the test and
properly delete the timer and wait for the body to finish using _sync
version of del_timer.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/parisc/kernel/pdc_cons.c

@@ -103,7 +103,7 @@ static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
 static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
 {
 	if (!tty->count)
-		del_timer(&pdc_console_timer);
+		del_timer_sync(&pdc_console_timer);
 }
 
 static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
@@ -153,7 +153,7 @@ static void pdc_console_poll(unsigned long unused)
 	if (count)
 		tty_flip_buffer_push(tty);
 
-	if (tty->count && (pdc_cons.flags & CON_ENABLED))
+	if (pdc_cons.flags & CON_ENABLED)
 		mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
 }