Revert "tty: don't panic on OOM in tty_set_ldisc()"

Revert "tty: don't panic on OOM in tty_set_ldisc()"

This reverts commit 5362544bebe85071188dd9e479b5a5040841c895 as it is
reported to cause a reproducable crash.

Fixes: 5362544bebe8 ("tty: don't panic on OOM in tty_set_ldisc()")
Reported-by: Vegard Nossum <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Peter Hurley <[email protected]>
Cc: One Thousand Gnomes <[email protected]>
Cc: Linus Torvalds <[email protected]>
Signed-off-by: Greg Kroah-Hartman [email protected]