ARM: S3C24XX: dma-s3c2443 - do not write into arbitary bits

The values read from the channel map always also contain the
DMA_CH_VALID (= 1<<31) setting, which should not get written
into the register, even if this bit is unused.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/mach-s3c24xx/dma-s3c2443.c

@@ -128,7 +128,8 @@ static struct s3c24xx_dma_map __initdata s3c2443_dma_mappings[] = {
 static void s3c2443_dma_select(struct s3c2410_dma_chan *chan,
 			       struct s3c24xx_dma_map *map)
 {
-	writel(map->channels[0] | S3C2443_DMAREQSEL_HW,
+	unsigned long chsel = map->channels[0] & (~DMA_CH_VALID);
+	writel(chsel | S3C2443_DMAREQSEL_HW,
 	       chan->regs + S3C2443_DMA_DMAREQSEL);
 }