dt/bindings: rcar-audmapp: tidyup dmas explanation

Current dmas explanation of SRC/DRS is confusable.
This patch clarifies it.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

Documentation/devicetree/bindings/dma/rcar-audmapp.txt

@@ -16,9 +16,9 @@ Example:
 * DMA client
 
 Required properties:
-- dmas:		a list of <[DMA multiplexer phandle] [SRS/DRS value]> pairs,
-		where SRS/DRS values are fixed handles, specified in the SoC
-		manual as the value that would be written into the PDMACHCR.
+- dmas:		a list of <[DMA multiplexer phandle] [SRS << 8 | DRS]> pairs.
+		where SRS/DRS are specified in the SoC manual.
+		It will be written into PDMACHCR as high 16-bit parts.
 - dma-names:	a list of DMA channel names, one per "dmas" entry
 
 Example: