interface: support configuring RSS steering queues

interface: support configuring RSS steering queues

This patch adds the RSS steering queues set interface, and it's
implementation in DPDK device:

/* Interface to set rss queues of the interface */
typedef clib_error_t *(vnet_interface_rss_queues_set_t)
  (struct vnet_main_t * vnm, struct vnet_hw_interface_t * hi,
   clib_bitmap_t *bitmap);

This patch also introduces a command line to set the RSS queues:
  set interface rss queues <interface> <list <queue-list>>
To display the rss queues, use "show hardware-interfaces"

Below is the example to configure rss queues for interface Gig0:
vpp# set interface rss queues Gig0 list 0,2,4-7
vpp# show hardware-interfaces brief
              Name                Idx   Link  Hardware
VirtualFunctionEthernet18/1/0      1    down  VirtualFunctionEthernet18/1/0
  Link speed: unknown
  RSS queues: 0 2 4 5 6 7
local0                             0    down  local0
  Link speed: unknown
vpp#

Users can also configure the rss queues on a dpdk interface in
startup.conf:
dpdk {
    dev 0000:18:01.0 {
        rss-queues 0,2,5-7
    }
}

Type: feature

Signed-off-by: Chenmin Sun <chenmin.sun@intel.com>
Change-Id: I1835595a1c54016a84eabee9fd62ce137935385d