IB/cma: Resolve route only while receiving CM requests

Currently CM request for RoCE follows following flow.
rdma_create_id()
rdma_resolve_addr()
rdma_resolve_route()
For RC QPs:
rdma_connect()
->cma_connect_ib()
  ->ib_send_cm_req()
    ->cm_init_av_by_path()
      ->ib_init_ah_attr_from_path()
For UD QPs:
rdma_connect()
->cma_resolve_ib_udp()
  ->ib_send_cm_sidr_req()
    ->cm_init_av_by_path()
      ->ib_init_ah_attr_from_path()

In both the flows, route is already resolved before sending CM requests.
Therefore, code is refactored to avoid resolving route second time in
ib_cm layer.
ib_init_ah_attr_from_path() is extended to resolve route when it is not
yet resolved for RoCE link layer. This is achieved by caller setting
route_resolved field in path record whenever it has route already
resolved.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

include/rdma/ib_sa.h

@@ -163,7 +163,15 @@ struct sa_path_rec_ib {
 	u8           raw_traffic;
 };
 
+/**
+ * struct sa_path_rec_roce - RoCE specific portion of the path record entry
+ * @route_resolved:	When set, it indicates that this route is already
+ *			resolved for this path record entry.
+ * @dmac:		Destination mac address for the given DGID entry
+ *			of the path record entry.
+ */
 struct sa_path_rec_roce {
+	bool	route_resolved;
 	u8           dmac[ETH_ALEN];
 	/* ignored in IB */
 	int	     ifindex;