The value of sapEgrQosHsmdaQueueMBS specifies the maximum buffer space
(MBS) override in bytes for the given egress hsmda queue on this SAP.
When set to default value, the MBS is not overridden and the MBS from
the sap-egress qos policy is honored. When a non-default value is
given, that is used instead of the MBS given in the sap-egress policy.