gpio: pxa: clamp gpio get value to [0,1]

It would be convenient to normalize the return value for gpio_get.

I have checked mach-mmp / mach-pxa / plat-pxa / plat-orion / mach-orion5x.
It's OK for all of them to change this function to return 0 and 1.
Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-pxa.c

@@ -263,7 +263,8 @@ static int pxa_gpio_direction_output(struct gpio_chip *chip,
 
 static int pxa_gpio_get(struct gpio_chip *chip, unsigned offset)
 {
-	return readl_relaxed(gpio_chip_base(chip) + GPLR_OFFSET) & (1 << offset);
+	u32 gplr = readl_relaxed(gpio_chip_base(chip) + GPLR_OFFSET);
+	return !!(gplr & (1 << offset));
 }
 
 static void pxa_gpio_set(struct gpio_chip *chip, unsigned offset, int value)