igb: Combine q_vector and ring allocation into a single function

This change combines the the allocation of q_vectors and rings into a single
function.  The advantage of this is that we are guaranteed we will avoid
overlap in the L1 cache sets.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>