IB/srp: Make transport layer retry count configurable

Allow the InfiniBand RC retry count to be configured by the user as an
option in the target login string.  Reducing this retry count allows to
reduce the path failover time.

Signed-off-by: Vu Pham <vu@mellanox.com>

[ bvanassche: Rewrote patch description / changed default retry count ]

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: David Dillow <dillowda@ornl.gov>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index e641088..84d821b 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -157,6 +157,7 @@
 	unsigned int		scsi_id;
 	unsigned int		sg_tablesize;
 	int			comp_vector;
+	int			tl_retry_count;
 
 	struct ib_sa_path_rec	path;
 	__be16			orig_dgid[8];