kokkos add "graviton" to spack_micro_arch_map (#19869)
kokkos add "graviton" to spack_micro_arch_map (#19869)

* kokkos add "graviton" to spack_micro_arch_map

* also add "graviton2"
iulian787/spack,iulian787/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack