PM / devfreq: rk3399_dmc: fix error return code in rk3399_dmcfreq_probe()

platform_get_irq() returns an error code, but the rk3399_dmc
driver ignores it and always returns -EINVAL. This is not correct,
and prevents -EPROBE_DEFER from being propagated properly.

Notice that platform_get_irq() no longer returns 0 on error:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e330b9a6bb35dc7097a4f02cb1ae7b6f96df92af

Print and propagate the return value of platform_get_irq on failure.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

drivers/devfreq/rk3399_dmc.c

@@ -336,8 +336,9 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
-		dev_err(&pdev->dev, "Cannot get the dmc interrupt resource\n");
-		return -EINVAL;
+		dev_err(&pdev->dev,
+			"Cannot get the dmc interrupt resource: %d\n", irq);
+		return irq;
 	}
 	data = devm_kzalloc(dev, sizeof(struct rk3399_dmcfreq), GFP_KERNEL);
 	if (!data)