igb: move SRRCTL register configuration into ring specific config

The SRRCTL register exists per ring.  Instead of configuring all of them in
the RCTL configuration which is meant to be global it makes more sense to move
this out into the ring specific 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>