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 <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>

drivers/gpio/gpiolib-acpi.c

···
 	struct acpi_gpio_lookup lookup;
 	int ret;
 
-	if (!adev)
-		return ERR_PTR(-ENODEV);
-
 	memset(&lookup, 0, sizeof(lookup));
 	lookup.index = index;