gpio: gpiolib: don't compare an unsigned for >= 0

The parameter offset is an unsigned, so it makes no sense to compare
it for >= 0. Fix the compiler warning regarding this by removing this
comparison.

As the macro GPIO_OFFSET_VALID is only used at this single place, simplify
the code by dropping the macro completely and dropping the invert, too.

No functional change.
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -47,8 +47,6 @@
  */
 DEFINE_SPINLOCK(gpio_lock);
 
-#define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)
-
 static DEFINE_MUTEX(gpio_lookup_lock);
 static LIST_HEAD(gpio_lookup_list);
 LIST_HEAD(gpio_chips);
@@ -995,7 +993,7 @@ const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
 {
 	struct gpio_desc *desc;
 
-	if (!GPIO_OFFSET_VALID(chip, offset))
+	if (offset >= chip->ngpio)
 		return NULL;
 
 	desc = &chip->desc[offset];