ice: Advertise virtchnl UDP segmentation offload capability

As the hardware is capable of supporting UDP segmentation offload, add a
capability bit to virtchnl.h to communicate this and have the driver
advertise its support.

Suggested-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>