The GbEth IP will pass through a zero UDP checksum without asserting any
error flags so we do not need to resort to software checksum calculation
in this case.
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>