Add ndo_ops to add/del UDP ports to a device that supports geneve
offload.

v2: Comment fix.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NKiran Patil <kiran.patil@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>