ARM: dts: qcom: msm8974-oneplus-bacon: Add notification LED

Add the node describing the sn3193 that's used to provide notification
LED.

Unfortunately the driver currently supports neither multicolor API nor
using the properties function & color, so we use label instead.

Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230122-msm8974-bacon-features-v2-5-06bb83c20a58@z3ntu.xyz