dt-bindings: leds: qcom,spmi-flash-led: Add PMI8998

Document compatible for PMI8998 Torch and Flash LED controller.

Signed-off-by: Dylan Van Assche <me@dylanvanassche.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230518133113.273880-2-me@dylanvanassche.be


Signed-off-by: Lee Jones <lee@kernel.org>