ionic: count csum_none when offload enabled

[ Upstream commit f07f9815 ]

Be sure to count the csum_none cases when csum offload is
enabled.

Fixes: 0f3154e6

 ("ionic: Add Tx and Rx handling")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>