IB/nes: Fix a race condition in nes_inetaddr_event()

This patch has been compile-tested only.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Faisal Latif <faisal.latif@intel.com>
Acked-by: Faisal Latif <fasial.latif@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>