This patch refactors tail bump check.

Change-ID: Ide0e19171d67d90cb2b06b8dcd4fa791ae120160
Signed-off-by: NCarolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>