[ofw] [PATCH] DAPL v2.0: common: increase default IB ack timer from 16 to 20

[Hefty, Sean]

> For larger, more congested fabrics, a larger ACK timer is needed.
> Consumers can still change default with environment variable
> DAPL_ACK_TIMER if they need to increase or decrease.
> 
> This applies to SCM and UCM providers only. The CMA provider, which
> uses rdma_cm, has no way to control ack timer with current API.

The rdma_cm uses the path lifetime to determine the QP timeout value.  The path record can be manipulated by the user when calling rdma_create_ep().

- Sean