Protect forwarding table with rwlock
Lock vioif_rx_deq correctly

It was not locked when called from vioif_stop_locked.
Don't use rwlock for forwarding table

Because forwarding tables are accessed in interrupt handlers.
Protect member list with mutex

We have to take care that list entries (bridge_iflist) can be
accessed out of bridge_lookup_member. So we have to free
a list entry (when a member is detached from a bridge) after
checking that it won't be referenced anymore.
Protect member list accessed in bridgestp.c as well