dt-bindings: pinctrl: Group tuples in pin control properties

To improve human readability and enable automatic validation, the tuples
in "pinctrl-*" properties should be grouped using angle brackets.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210204125718.1646082-1-geert+renesas@glider.be


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>