dmaengine: stm32-dma: remove unused ‘sfcr’

In stm32_dma_chan_irq(), variable ‘sfcr’ is initialized but never used, which
leads to warning with W=1

drivers/dma/stm32-dma.c: In function ‘stm32_dma_chan_irq’:
drivers/dma/stm32-dma.c:530:19: warning: variable ‘sfcr’ set but not used [-Wunused-but-set-variable]
  u32 status, scr, sfcr;

So remove it.
Reviewed-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/stm32-dma.c

@@ -527,13 +527,12 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
 {
 	struct stm32_dma_chan *chan = devid;
 	struct stm32_dma_device *dmadev = stm32_dma_get_dev(chan);
-	u32 status, scr, sfcr;
+	u32 status, scr;
 
 	spin_lock(&chan->vchan.lock);
 
 	status = stm32_dma_irq_status(chan);
 	scr = stm32_dma_read(dmadev, STM32_DMA_SCR(chan->id));
-	sfcr = stm32_dma_read(dmadev, STM32_DMA_SFCR(chan->id));
 
 	if ((status & STM32_DMA_TCI) && (scr & STM32_DMA_SCR_TCIE)) {
 		stm32_dma_irq_clear(chan, STM32_DMA_TCI);