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>
diff --git a/include/video/imx-ipu-v3.h b/include/video/imx-ipu-v3.h
index 8cb0768..ce4c076 100644
--- a/include/video/imx-ipu-v3.h
+++ b/include/video/imx-ipu-v3.h
@@ -250,6 +250,7 @@ struct ipu_image {
 
 void ipu_cpmem_zero(struct ipuv3_channel *ch);
 void ipu_cpmem_set_resolution(struct ipuv3_channel *ch, int xres, int yres);
+void ipu_cpmem_skip_odd_chroma_rows(struct ipuv3_channel *ch);
 void ipu_cpmem_set_stride(struct ipuv3_channel *ch, int stride);
 void ipu_cpmem_set_high_priority(struct ipuv3_channel *ch);
 void ipu_cpmem_set_buffer(struct ipuv3_channel *ch, int bufnum, dma_addr_t buf);