openvswitch: Move table destroy to dp-rcu callback.

Ths simplifies flow-table-destroy API. No need to pass explicit
parameter about context.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Thomas Graf <tgraf@redhat.com>

diff --cc net/openvswitch/datapath.c
Simple merge

diff --cc net/openvswitch/flow_table.c
Simple merge

diff --cc net/openvswitch/flow_table.h
Simple merge