staging: dgnc: delete dpatype board type variable.

It was only set, and never looked at, so drop the thing as no one cares
about it.

Cc: Lidza Louina <lidza.louina@gmail.com>
Cc: Mark Hounschell <markh@compro.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>