Add a description for the "qcom,mid" property which corresponds to the SPMI master ID of the SPMI PMIC arbiter controller. It is most useful in systems with multiple masters, e.g. when there are multiple SoCs connected to a single SPMI bus. Change-Id: I376e6f569f9bbea44ba3930480a330fb1dd2c2de Signed-off-by: Ayyagari Ushasreevalli <quic_aushasre@quicinc.com>