Userspace packet execute command pass down flow key for given
packet. But userspace can skip some parameter with zero value.
Therefore kernel needs to initialize key metadata to zero.

Fixes: 07148121 ("openvswitch: Eliminate memset() from flow_extract.")
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>