gpiolib: Extract gpiod_not_found() helper

Several places in the code are using same idiom, i.e.
	IS_ERR(desc) && PTR_ERR(desc) == -ENOENT
which meaning is GPIO description is not found.

For better readability extract gpiod_not_found() helper and use it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 2f895a2..9b22352 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -509,31 +509,31 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
 		desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
 						&of_flags);
 
-		if (!IS_ERR(desc) || PTR_ERR(desc) != -ENOENT)
+		if (!gpiod_not_found(desc))
 			break;
 	}
 
-	if (PTR_ERR(desc) == -ENOENT) {
+	if (gpiod_not_found(desc)) {
 		/* Special handling for SPI GPIOs if used */
 		desc = of_find_spi_gpio(dev, con_id, &of_flags);
 	}
 
-	if (PTR_ERR(desc) == -ENOENT) {
+	if (gpiod_not_found(desc)) {
 		/* This quirk looks up flags and all */
 		desc = of_find_spi_cs_gpio(dev, con_id, idx, flags);
 		if (!IS_ERR(desc))
 			return desc;
 	}
 
-	if (PTR_ERR(desc) == -ENOENT) {
+	if (gpiod_not_found(desc)) {
 		/* Special handling for regulator GPIOs if used */
 		desc = of_find_regulator_gpio(dev, con_id, &of_flags);
 	}
 
-	if (PTR_ERR(desc) == -ENOENT)
+	if (gpiod_not_found(desc))
 		desc = of_find_arizona_gpio(dev, con_id, &of_flags);
 
-	if (PTR_ERR(desc) == -ENOENT)
+	if (gpiod_not_found(desc))
 		desc = of_find_usb_gpio(dev, con_id, &of_flags);
 
 	if (IS_ERR(desc))