tty: moxa: use semi-colons instead of commas

This code works but it's cleaner to use a semi-colon to end a statement
instead of a comma.

Acked-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20210825072405.GA13013@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>