Do not reply in SendUnitData receive path in case of oversized, malformed, or mis-addressed requests

For devices with large assembly sizes (504 bytes), the EtherNet/IP Core must not send a reply in case of an error in the SendUnitData (CL3) encapsulation layer.

Specifically the case, oversized requests (larger than the connection size), is problematic. CL3 connections never respond directly. The O2T and T2O directions are unidirectional channels, despite they are technically running over the same TCP connection.

Desired behavior: The SendUnitData encapsulation command is not replied to anymore in case the received encapsulated packet is incorrect. 
Previously, error-replies were sent in case of invalid packets.