Apply review suggestion in linalg/kernels.hpp
Apply review suggestion in linalg/kernels.hpp

Co-authored-by: Yohann <322efd470ee11bd46d8b459d18c149ad8bfcf550@llnl.gov>
mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem