tty: deprecate tty_write_message()

tty_write_message() has only one user: quotas. In particular, there the
use depends on CONFIG_PRINT_QUOTA_WARNING. And that is deprecated and
marked as BROKEN already too.

So make tty_write_message() dependent on that very config option. This
action in fact drops tty_write_message() from the vmlinux binary. Good
riddance.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Jan Kara <jack@suse.com>
Acked-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231121092258.9334-2-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/tty_io.c

@@ -1047,6 +1047,7 @@ static ssize_t iterate_tty_write(struct tty_ldisc *ld, struct tty_struct *tty,
 	return ret;
 }
 
+#ifdef CONFIG_PRINT_QUOTA_WARNING
 /**
  * tty_write_message - write a message to a certain tty, not just the console.
  * @tty: the destination tty_struct
@@ -1057,6 +1058,8 @@ static ssize_t iterate_tty_write(struct tty_ldisc *ld, struct tty_struct *tty,
  * needed.
  *
  * We must still hold the BTM and test the CLOSING flag for the moment.
+ *
+ * This function is DEPRECATED, do not use in new code.
  */
 void tty_write_message(struct tty_struct *tty, char *msg)
 {
@@ -1069,6 +1072,7 @@ void tty_write_message(struct tty_struct *tty, char *msg)
 		tty_write_unlock(tty);
 	}
 }
+#endif
 
 static ssize_t file_tty_write(struct file *file, struct kiocb *iocb, struct iov_iter *from)
 {