[ciskip] HIP: Apply suggestions from code review

Co-authored-by: Damien L-G <dalg24+github@gmail.com>
Co-authored-by: Daniel Arndt <arndtd@ornl.gov>

core/src/HIP/Kokkos_HIP_Parallel_MDRange.hpp

@@ -200,8 +200,9 @@ class ParallelReduce<CombinedFunctorReducerType,
   // offset rather than at every 4 byte word; such that, when the join is
   // performed, we have the correct data that was copied over in chunks of 4
   // bytes.
+  static_assert(sizeof(size_type) == 4);
   using word_size_type = std::conditional_t<
-      sizeof(value_type) < sizeof(size_type),
+      sizeof(value_type) < 4,
       std::conditional_t<sizeof(value_type) == 2, int16_t, int8_t>, size_type>;
 
   // Algorithmic constraints: blockSize is a power of two AND blockDim.y ==
@@ -313,9 +314,9 @@ class ParallelReduce<CombinedFunctorReducerType,
                        : suggested_blocksize;  // Note: block_size must be less
                                                // than or equal to 512
 
-      m_scratch_space = (word_size_type*)hip_internal_scratch_space(
+      m_scratch_space = (reinterpret_cast<word_size_type*>(hip_internal_scratch_space(
           m_policy.space(), reducer.value_size() *
-                                block_size /* block_size == max block_count */);
+                                block_size /* block_size == max block_count */));
       m_scratch_flags =
           hip_internal_scratch_flags(m_policy.space(), sizeof(size_type));