[media] media: ti-vpe: vpdma: Fix bus error when vpdma is writing a descriptor

On DRA7 since l3_noc event are being reported it was found that
when the write descriptor was being written it was consistently
causing bus error events.

The write address was improperly programmed.

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>