gpio: renesas: Migrate to pinctrl GPIO accessors

Switch to generic pin controller API for configuring pins as GPIOs
instead of using the ad-hoc call into the R-Car PFC driver. Moreover,
add .free() implementation for the GPIO controller.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Alex Kiernan <alex.kiernan@gmail.com>
Cc: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Cc: Eugeniu Rosca <roscaeugeniu@gmail.com>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Patrick DELAUNAY <patrick.delaunay@st.com>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Cc: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/gpio-rcar.c b/drivers/gpio/gpio-rcar.c
index 6fd1270..594e0a4 100644
--- a/drivers/gpio/gpio-rcar.c
+++ b/drivers/gpio/gpio-rcar.c
@@ -6,6 +6,7 @@
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
+#include <dm/pinctrl.h>
 #include <errno.h>
 #include <asm/gpio.h>
 #include <asm/io.h>
@@ -117,19 +118,17 @@
 static int rcar_gpio_request(struct udevice *dev, unsigned offset,
 			     const char *label)
 {
-	struct rcar_gpio_priv *priv = dev_get_priv(dev);
-	struct udevice *pctldev;
-	int ret;
-
-	ret = uclass_get_device(UCLASS_PINCTRL, 0, &pctldev);
-	if (ret)
-		return ret;
+	return pinctrl_gpio_request(dev, offset);
+}
 
-	return sh_pfc_config_mux_for_gpio(pctldev, priv->pfc_offset + offset);
+static int rcar_gpio_free(struct udevice *dev, unsigned offset)
+{
+	return pinctrl_gpio_free(dev, offset);
 }
 
 static const struct dm_gpio_ops rcar_gpio_ops = {
 	.request		= rcar_gpio_request,
+	.free			= rcar_gpio_free,
 	.direction_input	= rcar_gpio_direction_input,
 	.direction_output	= rcar_gpio_direction_output,
 	.get_value		= rcar_gpio_get_value,