mtd: nand: mtk: fix error return code in mtk_ecc_probe()

platform_get_irq() returns an error code, but the mtk_ecc driver
ignores it and always returns -EINVAL. This is not correct and,
prevents -EPROBE_DEFER from being propagated properly.

Print and propagate the return value of platform_get_irq on failure.

This issue was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/mtk_ecc.c

@@ -464,8 +464,8 @@ static int mtk_ecc_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
-		dev_err(dev, "failed to get irq\n");
-		return -EINVAL;
+		dev_err(dev, "failed to get irq: %d\n", irq);
+		return irq;
 	}
 
 	ret = dma_set_mask(dev, DMA_BIT_MASK(32));