pinctrl: rza1: don't manually release devm managed resources

If the probe function fails the driver core cares to return the allocated
resources automatically. So the driver can be simplified accordingly.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>