gpio: Check if base is positive before calling gpio_is_valid()

It doesn't make much sense to make some (possible expensive) calls to
gpio_is_valid() first, and to ignore the result if the base number is
negative. Check for a positive base number first.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -227,8 +227,8 @@ int gpiochip_add(struct gpio_chip *chip)
 	unsigned	id;
 	int		base = chip->base;
 
-	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
-			&& base >= 0) {
+	if (base >= 0 &&
+	    (!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))) {
 		status = -EINVAL;
 		goto fail;
 	}