drivers/isdn/i4l/isdn_tty.c: remove write_sem

I couldn't find any users, so removing it..
Signed-off-by: NDaniel Walker <dwalker@mvista.com>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/isdn/i4l/isdn_tty.c

@@ -1917,7 +1917,6 @@ isdn_tty_modem_init(void)
 		info->owner = THIS_MODULE;
 #endif
 		spin_lock_init(&info->readlock);
-		init_MUTEX(&info->write_sem);
 		sprintf(info->last_cause, "0000");
 		sprintf(info->last_num, "none");
 		info->last_dir = 0;

include/linux/isdn.h

@@ -507,7 +507,6 @@ typedef struct modem_info {
   struct ktermios	normal_termios;  /* For saving termios structs     */
   struct ktermios	callout_termios;
   wait_queue_head_t	open_wait, close_wait;
-  struct semaphore      write_sem;
   spinlock_t	        readlock;
 } modem_info;