blackfin: gpio: 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.

Cc: Steven Miao <realmz6@gmail.com>
Cc: adi-buildroot-devel@lists.sourceforge.net
Acked-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/blackfin/kernel/bfin_gpio.c

@@ -1159,7 +1159,7 @@ static int bfin_gpiolib_direction_output(struct gpio_chip *chip, unsigned gpio,
 
 static int bfin_gpiolib_get_value(struct gpio_chip *chip, unsigned gpio)
 {
-	return bfin_gpio_get_value(gpio);
+	return !!bfin_gpio_get_value(gpio);
 }
 
 static void bfin_gpiolib_set_value(struct gpio_chip *chip, unsigned gpio, int value)