gpiolib: of: remove gpio_to_desc() usage

As demonstrated by commit
390d82e312c56b75407a3606cbcde8c4bc7f10ae
"gpiolib: ACPI: remove gpio_to_desc() usage"

gpio_to_desc() must die. Replace one of its usage by the
newly-introduced gpiochip_get_desc() function.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 2024d45..db98d3a 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -48,7 +48,7 @@
 	if (ret < 0)
 		return false;
 
-	gg_data->out_gpio = gpio_to_desc(ret + gc->base);
+	gg_data->out_gpio = gpiochip_get_desc(gc, ret);
 	return true;
 }