dmaengine: xilinx: xdma: Use resource_size() in xdma_probe()

There is a warning reported by coccinelle:

./drivers/dma/xilinx/xdma.c:888:22-25: ERROR:
	Missing resource_size with   res

Use resource_size() on resource object instead of explicit computation.
Signed-off-by: Li Zetao <lizetao1@huawei.com>
Link: https://lore.kernel.org/r/20230803033235.3049137-1-lizetao1@huawei.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/xilinx/xdma.c

@@ -883,7 +883,7 @@ static int xdma_probe(struct platform_device *pdev)
 		goto failed;
 	}
 	xdev->irq_start = res->start;
-	xdev->irq_num = res->end - res->start + 1;
+	xdev->irq_num = resource_size(res);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {