Instead of leaving the Rx timestamps in the same mode as before if we
disable the Rx logic, we can set it into a mode that has the fewest
possible timestamps generated. To do this, select only V1 mode, but do
not enable UDP packet recognition. This should eliminate all (or at
least almost all) Rx timestamps, since V1 packets are always over UDP.

Change-ID: If847288e0030a716e059c4c33ab114f2cf038f05
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Acked-by: NShannon Nelson <shannon.nelson@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>