OMCI-lib-go: Invalid code-generated Dot1ag ME attributes

Three of the 802.1ag Managed Entity attributes (below) are not decoded correctly by the OMCI document parser due to multiple attributes being defined on a single line. They are decode as a single Attribute with a real long name.

This can result in a failure on during a MIB upload next response decode since the Dot1AgChassisManagementInfo ME is automatically created if an ONU support 802.1ag or Y.1731. 

• Dot1AgChassisManagementInfo (ONU created)
• Dot1AgMaintenanceDomain   (OLT created)
• Dot1AgMaintenanceAssociation (OLT created)