dt-bindings: pinctrl: qcom,pmic-mpp: clean up example

dt-bindings: pinctrl: qcom,pmic-mpp: clean up example

The Multi-Purpose Pin controller block is part of an SPMI PMIC (which in
turns sits on an SPMI bus) and uses a single value for the register
property that corresponds to its base address.

Clean up the example by adding a parent PMIC node with proper
'#address-cells' and '#size-cells' properties, dropping the incorrect
second register value, adding some newline separators and increasing the
indentation to four spaces.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231130172834.12653-1-johan+linaro@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>