rhashtable_lookup_fast() internally calls rcu_read_lock() then,
calls rhashtable_lookup(). So if rcu_read_lock() is already held,
rhashtable_lookup() is enough.
Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>