igb: remove rx checksum good counter

Counting packets with a good checksum can cause a significant amount of cache
line bouncing due to the shared counter being written to by all of the queues.
In order to avoid this I am removing the counter since we still have the
checksum failed counter which will tell us if there are any issues.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>