i40e: use ktime_get_real_ts64 instead of ktime_to_timespec64

Remove a call to ktime_to_timespec64 by calling ktime_get_real_ts64
directly.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>