net: marvell: prestera: Add neighbour cache accounting

Move forward and use new PRESTERA_FIB_TYPE_UC_NH to provide basic
nexthop routes support.
Provide deinitialization sequence for all created router objects.

Limitations:
- Only "local" and "main" tables supported
- Only generic interfaces supported for router (no bridges or vlans)

Co-developed-by: Taras Chornyi <[email protected]>
Signed-off-by: Taras Chornyi <[email protected]>
Co-developed-by: Oleksandr Mazur <[email protected]>
Signed-off-by: Oleksandr Mazur <[email protected]>
Signed-off-by: Yevhen Orlov <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

Author: OrlovEI

drivers/net/ethernet/marvell/prestera/prestera.h

@@ -316,6 +316,7 @@ struct prestera_router {
 	struct rhashtable nh_neigh_ht;
 	struct rhashtable nexthop_group_ht;
 	struct rhashtable fib_ht;
+	struct rhashtable kern_neigh_cache_ht;
 	struct rhashtable kern_fib_cache_ht;
 	struct notifier_block inetaddr_nb;
 	struct notifier_block inetaddr_valid_nb;