Based on commit e0142726 ("igb: Break out Rx buffer page management")

Consolidate Rx code paths to reduce duplication when we expand them in
the future.
Signed-off-by: NEmil Tantilov <emil.s.tantilov@intel.com>
Tested-by: NKrishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>