IB/core: Add definition for the standard RoCE V2 UDP port

This will be used in hardware device driver when building QP or AH
contexts.
Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

include/rdma/ib_verbs.h

@@ -81,6 +81,7 @@ enum ib_gid_type {
 	IB_GID_TYPE_SIZE
 };
 
+#define ROCE_V2_UDP_DPORT      4791
 struct ib_gid_attr {
 	enum ib_gid_type	gid_type;
 	struct net_device	*ndev;