tty: moxa: Add support for CMSPAR

The mode constants are taken from the GPL-2.0+ driver available
in the driver section of the Moxa homepage.

It is tested on a C320Turbo PCI card per logic analyzer and
per a device which requires 9 bit character communication.

The vendors driver supports CMSPAR unconditionally, so that all
other available firmware versions seems to support mark/space
parity modes as well.

Signed-off-by: Lars Kanis <kanis@comcard.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>