i40e: separate TSYNVALID and TSYNINDX fields in Rx descriptor

In order to get 1588 to work correctly the defines need a bit
of a tweak.

Change-Id: Ie50ce2a18e1593441f1560411e5a4f51c6d48aaa
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>