gpu: ipu-v3: Add support for double read/write reduction

Allow to skip writing odd chroma rows by setting the RDRW bit for
4:2:0 chroma subsampled formats for any IDMAC write channel. This
also allows to skip reading odd rows for the VDIC read channel.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>