RDMA CM default RoCE mode not set on rxe_cfg add

[swelch]

When a Ethernet device is added, the RDMA CM default RoCE mode is not set by the rxe_cfg script. Therefore before the use of the RDMA CM for that device is possible, the rxe_cfg script must be used to stop and start softRoCE forcing the mode to be set when the persisted RXE device is added. The adding of an Ethernet device using "rxe_cfg add ethernet_if" should set the RDMA CM default RoCE mode.

[swelch]

An commit was added for review on branch iss-4 to make sure the same RXE device configuration is done when the Ethernet interface is initially added via "rxe_cfg add" as is done when a persisted interface is later added as part of "rxe_cfg start".