staging: dgnc: Fix do not add new typedefs

This patch fixes "do not add new typedefs"
checkpatch.pl warning in dgnc_types.h

Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>