linux-imx

IB/qib: Prevent context loss

If a context has already been assigned to an FD, prevent
another assignment.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>