gpiolib: acpi: Remove never true check in acpi_get_gpiod_by_index()

The acpi_get_gpiod_by_index() never is called with adev being NULL.
Remove the redundant check.
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpiolib-acpi.c

@@ -873,9 +873,6 @@ static struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
 	struct acpi_gpio_lookup lookup;
 	int ret;
 
-	if (!adev)
-		return ERR_PTR(-ENODEV);
-
 	memset(&lookup, 0, sizeof(lookup));
 	lookup.index = index;