i40e: Increase reset delay

Increase reset delay to ensure all internal caches are properly flushed
in worst case scenario.

Change-ID: I6f059a9e024fbf9ef1debd32497eed21369957fc
Signed-off-by: Kevin Scott <kevin.c.scott@intel.com>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>