dw_dmac: remove redundant check

There is no need to check the callback_required parameter, due to we check the
callback pointer to be a non-NULL.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/dw_dmac.c

@@ -347,7 +347,7 @@ dwc_descriptor_complete(struct dw_dma_chan *dwc, struct dw_desc *desc,
 
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
-	if (callback_required && callback)
+	if (callback)
 		callback(param);
 }