powerpc: ppc4cc/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: Anatolij Gustschin <agust@denx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

arch/powerpc/sysdev/ppc4xx_gpio.c

@@ -78,7 +78,7 @@ static int ppc4xx_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
 	struct ppc4xx_gpio __iomem *regs = mm_gc->regs;
 
-	return in_be32(&regs->ir) & GPIO_MASK(gpio);
+	return !!(in_be32(&regs->ir) & GPIO_MASK(gpio));
 }
 
 static inline void