tty: extract the pty init time special cases

The majority of the remaining init_dev code is pty special cases. We
refactor this code into the driver->install method.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 54523a3..3c7c757 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -401,9 +401,14 @@
 extern void proc_clear_tty(struct task_struct *p);
 extern struct tty_struct *get_current_tty(void);
 extern void tty_default_fops(struct file_operations *fops);
+extern struct tty_struct *alloc_tty_struct(void);
+extern void free_tty_struct(struct tty_struct *tty);
+extern void initialize_tty_struct(struct tty_struct *tty,
+		struct tty_driver *driver, int idx);
 extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
 								int first_ok);
 extern void tty_release_dev(struct file *filp);
+extern int tty_init_termios(struct tty_struct *tty);
 
 extern struct mutex tty_mutex;