TTY: con3215, add tty_port

And use flags from that. But first we have to get rid of duplicated
flag names. From now on, for the standard ones that are stored in
tty_port->flags, we use ASYNC_* ones.

Signed-off-by: Jiri 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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>