dt-bindings: usb: Correct indentation and style in DTS example

DTS example in the bindings should be indented with 2- or 4-spaces and
aligned with opening '- |', so correct any differences like 3-spaces or
mixtures 2- and 4-spaces in one binding.

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

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Andrew Jeffery <andrew@codeconstruct.com.au> # aspeed,usb-vhub.yaml
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Francesco Dolcini <francesco.dolcini@toradex.com> # ti,tusb73x0-pci.yaml
Acked-by: Florian Fainelli <florian.fainelli@broadcom.com> # brcm,bdc.yaml
Acked-by: Benjamin Bara <benjamin.bara@skidata.com> # cypress,hx3.yaml
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> # renesas
Link: https://lore.kernel.org/r/20250107131015.246461-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>