dt-bindings: pinctrl: aspeed: Use block syntax for function and groups

The expansion makes the documents a lot longer, but it's easier to
review changes to functions and groups when we're not having to deal
with line wrapping.

Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240531-dt-warnings-gpio-ast2600-pinctrl-funcs-groups-v1-1-a6fe2281a1b8@codeconstruct.com.au


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