gpio: tc3589x: Be sure to clamp return value

As we want gpio_chip .get() calls to be able to return negative
error codes and propagate to drivers, we need to go over all
drivers and make sure their return values are clamped to [0,1].
We do this by using the ret = !!(val) design pattern.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-tc3589x.c

@@ -51,7 +51,7 @@ static int tc3589x_gpio_get(struct gpio_chip *chip, unsigned offset)
 	if (ret < 0)
 		return ret;
 
-	return ret & mask;
+	return !!(ret & mask);
 }
 
 static void tc3589x_gpio_set(struct gpio_chip *chip, unsigned offset, int val)