raw3215[line] is set in probe, but not unset in remove. This will lead
to random crashes if the device is removed and the corresponding tty
opened later. open would dereference freed memory.

So set raw3215[line] to NULL in remove to fix that.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux390@de.ibm.com
Cc: linux-s390@vger.kernel.org
Acked-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>