Staging: dgnc: Remove unused fields in struct dgnc_board

Remove unused fields and comments associated with them in
the structure definition.

Signed-off-by: Srishti Sharma <srishtishar@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>