dw_dmac: fix copy/paste bug in tasklet

The tasklet checks RAW.BLOCK twice, and does not check RAW.XFER. This is
obviously wrong, and could theoretically cause the driver to hang.

Reported-by: Nicolas Ferre <[e-mail]>
Signed-off-by: Haavard Skinnemoen <[e-mail]>
Acked-by: Dan Williams <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/dma/dw_dmac.c

···
 	int i;
 
 	status_block = dma_readl(dw, RAW.BLOCK);
-	status_xfer = dma_readl(dw, RAW.BLOCK);
+	status_xfer = dma_readl(dw, RAW.XFER);
 	status_err = dma_readl(dw, RAW.ERROR);
 
 	dev_vdbg(dw->dma.dev, "tasklet: status_block=%x status_err=%x\n",