TTY: switch tty_insert_flip_char

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_char is the next one to proceed. This one is used all
over the code, so the patch is huge.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/digi_acceleport.c

@@ -1441,7 +1441,7 @@ static int digi_read_inb_callback(struct urb *urb)
 
 		/* overrun is special, not associated with a char */
 		if (port_status & DIGI_OVERRUN_ERROR)
-			tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+			tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);
 
 		/* break takes precedence over parity, */
 		/* which takes precedence over framing errors */