tty: make tty_release_redirect() static

No one calls this outside of the tty_io.c file, so mark this static and
do not export the symbol anymore.

Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210408125134.3016837-11-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_io.c

@@ -547,7 +547,7 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
  *	This is available to the pty code so if the master closes, if the
  *	slave is a redirect it can release the redirect.
  */
-struct file *tty_release_redirect(struct tty_struct *tty)
+static struct file *tty_release_redirect(struct tty_struct *tty)
 {
 	struct file *f = NULL;
 
@@ -560,7 +560,6 @@ struct file *tty_release_redirect(struct tty_struct *tty)
 
 	return f;
 }
-EXPORT_SYMBOL_GPL(tty_release_redirect);
 
 /**
  *	__tty_hangup		-	actual handler for hangup events

include/linux/tty.h

@@ -396,7 +396,6 @@ extern struct tty_struct *tty_kopen_shared(dev_t device);
 extern void tty_kclose(struct tty_struct *tty);
 extern int tty_dev_name_to_number(const char *name, dev_t *number);
 extern ssize_t redirected_tty_write(struct kiocb *, struct iov_iter *);
-extern struct file *tty_release_redirect(struct tty_struct *tty);
 #else
 static inline void tty_kref_put(struct tty_struct *tty)
 { }