pinctrl: ish-pfc: Use devm_pinctrl_register() for pinctrl registration

Use devm_pinctrl_register() for pin control registration.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: linux-renesas-soc@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>