dt-bindings: power: supply: Correct indentation and style in DTS example

dt-bindings: power: supply: Correct indentation and style in DTS example

DTS example in the bindings should be indented with 2- or 4-spaces and
aligned with opening '- |'. Correct mixtures of the style or any other
indentations to use preferred 4-spaces.

No functional changes here, but saves some comments during reviews
of new patches built on the existing code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250318081428.33979-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>