dt-bindings: net: litex,liteeth: Correct example indentation

DTS example in the bindings should be indented with 2- or 4-spaces, so
correct a mixture of different styles to keep consistent 4-spaces.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Gabriel Somlo <gsomlo@gmail.com>
Link: https://patch.msgid.link/20250821083038.46274-3-krzysztof.kozlowski@linaro.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>