The value of tSapEgressFCQGrpFC, when specified, will replace the
forwarding class derived from ingress as the forwarding class to
use inside the egress queue group. tSapEgressFCQGrpFC is only
allowed to be used in conjunction with egress policers, and is
mutually exclusive with direct queue-group queue mappings.
An 'inconsistentValue' error is returned if tSapEgressFCQGrpFC is
set to a non-default value when tSapEgressFCPolicer is set to default.