staging: dgap: Add Mark Hounschell to maintainers list for dgap

Add Mark Hounschell to the MAINTAINERs list for the dgap driver

Signed-off-by: Mark Hounschell <markh@compro.net>
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>