igb: make rxcsum configuration seperate from multiqueue

The igb driver was being incorrectly setup to only allow disabling receive
checksum if multiqueue was disabled.  This change corrects that so that
RXCSUM is configured regardless of queue configuration.

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>