RDMA/iwcm: Fix comment for iwcm_deref_id() to match code

RDMA/iwcm: Fix comment for iwcm_deref_id() to match code

In iwcm_deref_id(), the comment says : "If the last reference is being
removed and iw_destroy_cm_id is waiting, wake up the waiting
thread". The second part of the comment, "and iw_destroy_cm_id is
waiting," is wrong, since this function either wakes the waiter
already waiting in iwcm_deref_id, or enables it (so that when
wait_for_completion() is performed later, it will immediately return).

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>