Input: twl4030_keypad - Fix handling of platform_get_irq() error

platform_get_irq() returns -ERRNO on error.  In such case comparison
to 0 would pass the check.

Fixes: 7abf38d ("Input: twl4030-keypad - add device tree support")
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/input/keyboard/twl4030_keypad.c

@@ -376,10 +376,8 @@ static int twl4030_kp_probe(struct platform_device *pdev)
 	}
 
 	kp->irq = platform_get_irq(pdev, 0);
-	if (!kp->irq) {
-		dev_err(&pdev->dev, "no keyboard irq assigned\n");
-		return -EINVAL;
-	}
+	if (kp->irq < 0)
+		return kp->irq;
 
 	error = matrix_keypad_build_keymap(keymap_data, NULL,
 					   TWL4030_MAX_ROWS,