i40e: set max limit for access polling

Don't bother trying to set a smaller timeout on the polling,
just simplify the code and always use the max limit.  Also,
rename a variable for clarity and fix a comment.

Change-ID: I0300c3562ccc4fd5fa3088f8ae52db0c1eb33af5
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Acked-by: Michal Kosiarz <michal.kosiarz@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>