imx-sdma: remove useless variable

last_used variable is applied only once, so, let's substitute it by its value.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/imx-sdma.c

@@ -1124,11 +1124,8 @@ static enum dma_status sdma_tx_status(struct dma_chan *chan,
 				      struct dma_tx_state *txstate)
 {
 	struct sdma_channel *sdmac = to_sdma_chan(chan);
-	dma_cookie_t last_used;
 
-	last_used = chan->cookie;
-
-	dma_set_tx_state(txstate, chan->completed_cookie, last_used,
+	dma_set_tx_state(txstate, chan->completed_cookie, chan->cookie,
 			sdmac->chn_count - sdmac->chn_real_count);
 
 	return sdmac->status;