datapath: Make OVS_ACTION_ATTR_USERSPACE action to send packet key

datapath: Make OVS_ACTION_ATTR_USERSPACE action to send packet key

OVS_ACTION_ATTR_USERSPACE action was sending the key from the matching
flow. This works for exact match flows because flow keys are the
same as packet keys. However, it does not work with wildcarded flows as
the packet keys may be different than the flow keys. This patch uses
the packet keys carried in OVS_CB(skb) when calling output_userspace().

Bug #18163

Signed-off-by: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>