arm64: dts: marvell: uDPU: align LED-s with bindings

According to bindings they LED-s should be prefixed with "led" in this
use case, so fix accordingly.

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>