Revert "tty: Fix ldisc crash on reopened tty"

This reverts commit 71472fa9.  It caused
merge issues, and Dmitry found some review issues.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Michael Neuling <mikey@neuling.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>