dmaengine: rcar-dmac: clear pertinence number of channels

DMACHCLR clears each channels, but its channel number is based on
its SoC or IP. Current driver is using fixed 0x7fff (= for 15ch),
it is not good match for Gen3 or Gen2 Audio DMAC. This patch fixes it

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/sh/rcar-dmac.c

@@ -413,7 +413,7 @@ static int rcar_dmac_init(struct rcar_dmac *dmac)
 	u16 dmaor;
 
 	/* Clear all channels and enable the DMAC globally. */
-	rcar_dmac_write(dmac, RCAR_DMACHCLR, 0x7fff);
+	rcar_dmac_write(dmac, RCAR_DMACHCLR, GENMASK(dmac->n_channels - 1, 0));
 	rcar_dmac_write(dmac, RCAR_DMAOR,
 			RCAR_DMAOR_PRI_FIXED | RCAR_DMAOR_DME);