datapath: Simplify do_execute_actions().

datapath: Simplify do_execute_actions().

Upstream commit:
    commit 5b8784aaf29be20ba8d363e1124d7436d42ef9bf
    Author: Andy Zhou <azhou@ovn.org>
    Date: Fri Jan 27 13:45:28 2017 -0800

    openvswitch: Simplify do_execute_actions().

    do_execute_actions() implements a worthwhile optimization: in case
    an output action is the last action in an action list, skb_clone()
    can be avoided by outputing the current skb. However, the
    implementation is more complicated than necessary.  This patch
    simplify this logic.

    Signed-off-by: Andy Zhou <azhou@ovn.org>
    Acked-by: Pravin B Shelar <pshelar@ovn.org>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Upstream: 5b8784aaf29b ("openvswitch: Simplify do_execute_actions().")
Signed-off-by: Joe Stringer <joe@ovn.org>
Acked-by: Jarno Rajahalme <jarno@ovn.org>