netdev: Dynamic per-port Flow API.

Current issues with Flow API:

* OVS calls offloading functions regardless of successful
  flow API initialization. (ex. on init_flow_api failure)
* Static initilaization of Flow API for a netdev_class forbids
  having different offloading types for different instances
  of netdev with the same netdev_class. (ex. different vports in
  'system' and 'netdev' datapaths at the same time)

Solution:

* Move Flow API from the netdev_class to netdev instance.
* Make Flow API dynamic, i.e. probe the APIs and choose the
  suitable one.

Side effects:

* Flow API providers localized as possible in their modules.
* Now we have an ability to make runtime checks. For example,
  we could check if particular device supports features we
  need, like if dpdk device supports RSS+MARK action.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Acked-by: Roi Dayan <roid@mellanox.com>

lib/netdev-vport.c

@@ -47,7 +47,6 @@
 #include "unaligned.h"
 #include "unixctl.h"
 #include "openvswitch/vlog.h"
-#include "netdev-tc-offloads.h"
 #ifdef __linux__
 #include "netdev-linux.h"
 #endif
@@ -1116,10 +1115,8 @@ netdev_vport_get_ifindex(const struct netdev *netdev_)
 }
 
 #define NETDEV_VPORT_GET_IFINDEX netdev_vport_get_ifindex
-#define NETDEV_FLOW_OFFLOAD_API , LINUX_FLOW_OFFLOAD_API
 #else /* !__linux__ */
 #define NETDEV_VPORT_GET_IFINDEX NULL
-#define NETDEV_FLOW_OFFLOAD_API
 #endif /* __linux__ */
 
 #define VPORT_FUNCTIONS_COMMON                      \
@@ -1133,8 +1130,7 @@ netdev_vport_get_ifindex(const struct netdev *netdev_)
     .get_etheraddr = netdev_vport_get_etheraddr,    \
     .get_stats = netdev_vport_get_stats,            \
     .get_pt_mode = netdev_vport_get_pt_mode,        \
-    .update_flags = netdev_vport_update_flags       \
-    NETDEV_FLOW_OFFLOAD_API
+    .update_flags = netdev_vport_update_flags
 
 #define TUNNEL_FUNCTIONS_COMMON                     \
     VPORT_FUNCTIONS_COMMON,                         \