This is the snippet from my patch to my DTS file that enables the slave queue, along with multi-master on i2c0.
+&i2c0 {
+ multi-master = <1>;
+ status = "okay";
+
+ ipmb0 at 10 {
+ compatible = "slave-mqueue";
+ reg = <(0x10 | I2C_OWN_SLAVE_ADDRESS)>;
+ message-size = <256>;
+ queue-size = <32>;
+ };
+};