ixgbe: Correct several flaws with with DCA setup

This change does two things. First, it makes it so that we always
set the relaxed ordering bits related to the DCA registers even if
DCA is not enabled. Second, it moves the configuration out of the
ixgbe_down function and into the ixgbe_configure function before
enabling the Rx and Tx rings. This ensures that DCA is configured
correctly before starting to process packets.

Thanks to Alex Duyck for this fix.

CC: Alex Duyck <aduyck@mirantis.com>
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>