drivers/net/ixgbe/ixgbe_main.c: Add ixgbe_psum

Reduce indentation in a couple of places
Add static function ixgbe_psum
Add temporary for adapter->stats

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>