dmaengine: ep93xx: Fix a NULL vs IS_ERR() check in probe()

This was intended to be an IS_ERR() check, not a NULL check.  The
ep93xx_dma_of_probe() function doesn't return NULL pointers.

Fixes: 4e8ad5ed845b ("dmaengine: cirrus: Convert to DT for Cirrus EP93xx")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/dma/ep93xx_dma.c

@@ -1504,7 +1504,7 @@ static int ep93xx_dma_probe(struct platform_device *pdev)
 	int ret;
 
 	edma = ep93xx_dma_of_probe(pdev);
-	if (!edma)
+	if (IS_ERR(edma))
 		return PTR_ERR(edma);
 
 	dma_dev = &edma->dma_dev;