RDMA/cxgb3: Handle EEH events

- wrap calls into cxgb3 and fail them if we're in the middle
  of a PCI EEH event.

- correctly unwind and release endpoint and other resources when
  we are in an EEH event.

- dispatch IB_EVENT_DEVICE_FATAL event when cxgb3 notifies iw_cxgb3 of
  a fatal error.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>