gpu: ipu-v3: Rename and add IDMAC channels

Rename the ENC/VF/PP rotation channel names, to be more consistent
with the convention that *_MEM is write-to-memory channels and
MEM_* is read-from-memory channels. Also add the channels who's
source and destination is the IC.

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>