Fix mismerge in OFED update

When OFED was upgraded to Linux v4.9, a bunch of Linux-specific
netlink changes were dropped.  Unfortunately, there was a mismerge
in this process and as a result ib_sa_cancel_query() would fail to
cancel an outstanding MAD.

This was causing rdma_destroy_id() to hang indefinitely waiting
for the MAD to complete and release the final reference.

Sponsored by: Dell Inc.
Differential Revision:	https://reviews.freebsd.org/D28421
Reviewed by: hselasky, kib
MFC after: 2 months

sys/ofed/drivers/infiniband/core/ib_sa_query.c

@@ -622,6 +622,8 @@ void ib_sa_cancel_query(int id, struct ib_sa_query *query)
 	agent = query->port->agent;
 	mad_buf = query->mad_buf;
 	spin_unlock_irqrestore(&idr_lock, flags);
+
+	ib_cancel_mad(agent, mad_buf);
 }
 EXPORT_SYMBOL(ib_sa_cancel_query);