Char: moxa, remove unused variables

drivers/tty/moxa.c:1287:2: warning: Value stored to 'port' is never read
        port = tty->index;
        ^      ~~~~~~~~~~
drivers/tty/moxa.c:1763:2: warning: Value stored to 'cflag' is never read
        cflag = termio->c_cflag;        /* termio->c_cflag */
        ^       ~~~~~~~~~~~~~~~

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>