Blackfin arch: dma code: cannot simply OR the ndsize

cannot simply OR the ndsize ... need to clear out the old value first
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>

arch/blackfin/include/asm/dma.h

@@ -205,7 +205,9 @@ static inline unsigned long get_dma_curr_addr(unsigned int channel)
 
 static inline void set_dma_sg(unsigned int channel, struct dmasg *sg, int ndsize)
 {
-	dma_ch[channel].regs->cfg |= ((ndsize & 0x0F) << 8);
+	dma_ch[channel].regs->cfg =
+		(dma_ch[channel].regs->cfg & ~(0xf << 8)) |
+		((ndsize & 0xf) << 8);
 	dma_ch[channel].regs->next_desc_ptr = sg;
 }