ECS: Increase the DPM mailbox sizes

ECS: Increase the DPM mailbox pool sizes, because the TX mailbox may can block.
This may can happen under special conditions:

• when the CTT performs the state machine test with accelerated state transition timings in the ESI file AND
• the netIC host application uses the netIC acayclic packet communication AND
• the netIC host application is registered for indications AND
• the netIC host application is send addition packet requests