remove unused file

src/KOKKOS/kissfft_kokkos.cpp

@@ -1,21 +0,0 @@
-// clang-format off
-/* ----------------------------------------------------------------------
-   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
-   https://www.lammps.org/, Sandia National Laboratories
-   Steve Plimpton, sjplimp@sandia.gov
-
-   Copyright (2003) Sandia Corporation.  Under the terms of Contract
-   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
-   certain rights in this software.  This software is distributed under
-   the GNU General Public License.
-
-   See the README file in the top-level LAMMPS directory.
-------------------------------------------------------------------------- */
-
-
-namespace LAMMPS_NS {
-template class KissFFTKokkos<LMPDeviceType>;
-#ifdef LMP_KOKKOS_GPU
-template class KissFFTKokkos<LMPHostType>;
-#endif
-}