datapath: simplify the ovs_dp_cmd_new

datapath: simplify the ovs_dp_cmd_new

Upstream commit:
    commit eec62eadd1d757b0743ccbde55973814f3ad396e
    Author: Tonghao Zhang <xiangxia.m.yue@gmail.com>
    Date:   Fri Nov 1 22:23:54 2019 +0800

    net: openvswitch: simplify the ovs_dp_cmd_new

    use the specified functions to init resource.

    Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
    Tested-by: Greg Rose <gvrose8192@gmail.com>
    Acked-by: Pravin B Shelar <pshelar@ovn.org>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Acked-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Greg Rose <gvrose8192@gmail.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>