[media] drx-j: Prepare to use DVBv5 stats

Convert the stats internally to use DVBv5. For now, it will keep
showing everything via DVBv3 API only, as the .len value were
not initialized.

That allows testing if the new stats code didn't break anything.

A latter patch will add the final bits for the DVBv5 stats to
fully work.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>