gpio: rcar: Fix error path for devm_kzalloc() failure

If the call to devm_kzalloc() fails, nothing must be cleant up.
This was missed before because gpio_rcar_probe() had a "return"
statement after the first "goto err0".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: df0c6c80 ("gpio: rcar: Add minimal runtime PM support")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>