arm64: dts: qcom: sm8550-qrd: add flash LEDs

Enable PM8550 PMIC flash LED controller and add two flash LEDs using
four current outputs.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230516150202.188655-3-krzysztof.kozlowski@linaro.org