arm64: dts: marvell: uDPU: remove LED node pinctrl-names

Using pinctrl-names requires the appropriate pinctrl-0 property, otherwise
it is not utilized at all.

Since its not required, just remove it.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>