EX-2596 build: add ddn tag to build MOFED

EX-2596 build: add ddn tag to build MOFED

We need to add ddn tag to MOFED kmod build
to indicate that kmod-mlnx-ofed_kernel is different
from the stock version

Test-Parameters: trivial

Change-Id: Ibc8b95c228afa921cedbc30d74196754e0f0cc24
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/41879
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>