arm64: dts: qcom: sdm845: Enable user LEDs on DB845c

The DB845c has 4 "user LEDs", the last one is already supported as it's
just wired to a gpio. Now that the LPG binding is in place we can wire
up the other 3 LEDs as well.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Caleb Connolly <caleb@connolly.tech>
Reviewed-by: Dylan Van Assche <me@dylanvanassche.be>
Link: https://lore.kernel.org/r/20220505022706.1692554-3-bjorn.andersson@linaro.org