sfc: do not try to call tc functions when CONFIG_SFC_SRIOV=n

Functions efx_tc_netdev_event and efx_tc_netevent_event do not exist
in that case as object files tc_bindings.o and tc_encap_actions.o
are not built, so the calls to them from ef100_netdev_event and
ef100_netevent_event cause link errors.
Wrap the corresponding header files (tc_bindings.h, tc_encap_actions.h)
with #if IS_ENABLED(CONFIG_SFC_SRIOV), and add an #else with static
inline stubs for these two functions.

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Fixes: 7e5e7d800011 ("sfc: neighbour lookup for TC encap action offload")
Signed-off-by: Edward Cree <[e-mail]>
Reviewed-by: Martin Habets <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/sfc/tc_bindings.h

···
 #define EFX_TC_BINDINGS_H
 #include "net_driver.h"
 
+#if IS_ENABLED(CONFIG_SFC_SRIOV)
 #include <net/sch_generic.h>
 
 struct efx_rep;
···
 			 void (*cleanup)(struct flow_block_cb *block_cb));
 int efx_tc_netdev_event(struct efx_nic *efx, unsigned long event,
 			struct net_device *net_dev);
+
+#else /* CONFIG_SFC_SRIOV */
+
+static inline int efx_tc_netdev_event(struct efx_nic *efx, unsigned long event,
+				      struct net_device *net_dev)
+{
+	return NOTIFY_DONE;
+}
+
+#endif /* CONFIG_SFC_SRIOV */
+
 #endif /* EFX_TC_BINDINGS_H */

drivers/net/ethernet/sfc/tc_encap_actions.h

···
 #define EFX_TC_ENCAP_ACTIONS_H
 #include "net_driver.h"
 
+#if IS_ENABLED(CONFIG_SFC_SRIOV)
 #include <linux/refcount.h>
 #include <net/tc_act/tc_tunnel_key.h>
 
···
 void efx_tc_unregister_egdev(struct efx_nic *efx, struct net_device *net_dev);
 int efx_tc_netevent_event(struct efx_nic *efx, unsigned long event,
 			  void *ptr);
+
+#else /* CONFIG_SFC_SRIOV */
+
+static inline int efx_tc_netevent_event(struct efx_nic *efx,
+					unsigned long event, void *ptr)
+{
+	return NOTIFY_DONE;
+}
+
+#endif /* CONFIG_SFC_SRIOV */
 
 #endif /* EFX_TC_ENCAP_ACTIONS_H */