examples/l3fwd-power: support virtio/vhost

examples/l3fwd-power: support virtio/vhost

In l3fwd-power, there is default port configuration which requires
RSS and IPv4/UDP/TCP checksum. Once device does not support these,
the l3fwd-power will exit and report an error.
This patch updates the port configuration based on device capabilities
after getting the device information to support devices like virtio
and vhost.

Signed-off-by: Miao Li <miao.li@intel.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>