netdev-provider: Apply batch object to netdev provider.

netdev-provider: Apply batch object to netdev provider.

Commit 1895cc8dbb64 ("dpif-netdev: create batch object") introduces
batch process functions and 'struct dp_packet_batch' to associate with
batch-level metadata.  This patch applies the packet batch object to
the netdev provider interface (dummy, Linux, BSD, and DPDK) so that
batch APIs can be used in providers.  With batch metadata visible in
providers, optimizations can be introduced at per-batch level instead
of per-packet.

Tested-at: https://travis-ci.org/williamtu/ovs-travis/builds/145694197
Signed-off-by: William Tu <u9012063@gmail.com>
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>