dmaengine: Mark the struct dma_slave_config direction field deprecated

The direction passed to the device_prep_slave_sg, device_prep_dma_cyclic
or device_prep_interleaved_dma (through struct dma_interleaved_template)
should be used instead.
Signed-off-by: NLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>

include/linux/dmaengine.h

@@ -307,7 +307,9 @@ enum dma_slave_buswidth {
  * struct dma_slave_config - dma slave channel runtime config
  * @direction: whether the data shall go in or out on this slave
  * channel, right now. DMA_MEM_TO_DEV and DMA_DEV_TO_MEM are
- * legal values.
+ * legal values. DEPRECATED, drivers should use the direction argument
+ * to the device_prep_slave_sg and device_prep_dma_cyclic functions or
+ * the dir field in the dma_interleaved_template structure.
  * @src_addr: this is the physical address where DMA slave data
  * should be read (RX), if the source is memory this argument is
  * ignored.