virtio: split gso and checksum offload functionality

Type: refactor

Change-Id: I897e36bd5db593b417c2bac9f739bc51cf45bc08
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>
diff --git a/src/vnet/devices/virtio/virtio.h b/src/vnet/devices/virtio/virtio.h
index 27ecc22..4b86626 100644
--- a/src/vnet/devices/virtio/virtio.h
+++ b/src/vnet/devices/virtio/virtio.h
@@ -174,6 +174,7 @@
   u8 host_ip6_prefix_len;
   u32 host_mtu_size;
   int gso_enabled;
+  int csum_offload_enabled;
   int ifindex;
   virtio_vring_t *cxq_vring;
 } virtio_if_t;