RDMA/cma: Increase the IB CM retry count in CMA

3 seems like a low number of IB Communication Manager retries to set;
we see connections failing under stress, and in any case 3 just looks
like an arbitrary number.  15 is the max value allowed by the
InfiniBand spec.
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Acked-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/cma.c

@@ -49,7 +49,7 @@ MODULE_DESCRIPTION("Generic RDMA CM Agent");
 MODULE_LICENSE("Dual BSD/GPL");
 
 #define CMA_CM_RESPONSE_TIMEOUT 20
-#define CMA_MAX_CM_RETRIES 3
+#define CMA_MAX_CM_RETRIES 15
 
 static void cma_add_one(struct ib_device *device);
 static void cma_remove_one(struct ib_device *device);