The VPDMA (Video Port DMA) as found in devices such as DRA7xx is
used for both the Video Processing Engine (VPE) and the Video Input
Port (VIP). Some devices may have multiple VIP instances each with
its own VPDMA engine. Within VIP two slices can use a single VPDMA
engine simultaneously. So support for multi instances and multiple
clients has been added to VPDMA. Needed modification to the existing
helper functions were then reflected to VPE.

Multi-clients registers offset have also been added in preparation.
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>