MAINTAINERS: Add Renesas RZ/A and RZ/N files to Renesas pinctrl section

Add paths for the Renesas RZ/A and RZ/N series pin controller drivers,
as they are not under sh-pfc/, but still maintained with the other
Renesas pin controller drivers.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>