dmaengine: stm32-dmamux: set dmamux channel id in dma features bitfield

STM32 DMAMUX is used with STM32 DMA1 and DMA2:
- DMAMUX channels 0 to 7 are connected to DMA1 channels 0 to 7
- DMAMUX channels 8 to 15 are connected to DMA2 channels 0 to 7

STM32 MDMA can be triggered by DMA1 and DMA2 channels transfer complete,
and the "request line number" is the DMAMUX channel id (e.g. DMA2 channel 0
triggers MDMA with request line 8).

To well configure MDMA, set DMAMUX channel id in DMA features bitfield,
so that DMA can update struct dma_slave_config peripheral_config properly.
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20220829154646.29867-5-amelie.delaunay@foss.st.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/stm32-dmamux.c

@@ -147,7 +147,7 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 	mux->request = dma_spec->args[0];
 
 	/*  craft DMA spec */
-	dma_spec->args[3] = dma_spec->args[2];
+	dma_spec->args[3] = dma_spec->args[2] | mux->chan_id << 16;
 	dma_spec->args[2] = dma_spec->args[1];
 	dma_spec->args[1] = 0;
 	dma_spec->args[0] = mux->chan_id - min;