tty: The big operations rework

- Operations are now a shared const function block as with most other Linux
  objects

- Introduce wrappers for some optional functions to get consistent behaviour

- Wrap put_char which used to be patched by the tty layer

- Document which functions are needed/optional

- Make put_char report success/fail

- Cache the driver->ops pointer in the tty as tty->ops

- Remove various surplus lock calls we no longer need

- Remove proc_write method as noted by Alexey Dobriyan

- Introduce some missing sanity checks where certain driver/ldisc
  combinations would oops as they didn't check needed methods were present

[akpm@linux-foundation.org: fix fs/compat_ioctl.c build]
[akpm@linux-foundation.org: fix isicom]
[akpm@linux-foundation.org: fix arch/ia64/hp/sim/simserial.c build]
[akpm@linux-foundation.org: fix kgdb]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/usb/serial/whiteheat.c

@@ -673,15 +673,13 @@ static void whiteheat_close(struct usb_serial_port *port, struct file * filp)
 	}
 */
 
-	if (port->tty->driver->flush_buffer)
-		port->tty->driver->flush_buffer(port->tty);
+	tty_driver_flush_buffer(port->tty);
 	tty_ldisc_flush(port->tty);
 
 	firm_report_tx_done(port);
 
 	firm_close(port);
 
-printk(KERN_ERR"Before processing rx_urbs_submitted.\n");
 	/* shutdown our bulk reads and writes */
 	mutex_lock(&info->deathwarrant);
 	spin_lock_irq(&info->lock);