platform/x86: intel_mid_powerbtn: fix error return code in mid_pb_probe()

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

Print error message and propagate the return value of platform_get_irq
on failure.

This issue was detected with the help of Coccinelle.
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel_mid_powerbtn.c

@@ -142,8 +142,10 @@ static int mid_pb_probe(struct platform_device *pdev)
 	if (!id)
 		return -ENODEV;
 
-	if (irq < 0)
-		return -EINVAL;
+	if (irq < 0) {
+		dev_err(&pdev->dev, "Failed to get IRQ: %d\n", irq);
+		return irq;
+	}
 
 	input = devm_input_allocate_device(&pdev->dev);
 	if (!input)