tty: ipwireless: Remove tty->closing abort from ipw_open()

tty->closing cannot be set on ipw_open() because the ipwireless tty
driver does not call any functions that set tty->closing.

CC: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>