ixgbe: pull ring configuration into it's own function

These changes add ixgbe_configure_rx_ring which is used to setup the base
function pointers for the ring.

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>