arm64: dts: renesas: Fix pin controller node names

Align all pin controller node names with the expectations of the DT
bindings in Documentation/devicetree/bindings/pinctrl/pinctrl.yaml.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/09a09c8ac9cb1a11b859c1ab9d9eae84cfefb1bb.1639666967.git.geert+renesas@glider.be