message: Simplify MakeBlockMap now that we aren't dealing with 16-bit quantities
  anymore.
  There is still some assumption in GetBlockByIndex's bit operations that
  some quantities fit in uint16. We'll clarify that and write unit tests
  once the current wave of simplification settles.
diff: @@ -167,18 +167,14 @@ void MakeBlockMap(int rows, int cols, int depth, int kernel_rows,
  ceil_log2(std::max(lhs_scalar_size, rhs_scalar_size)));
  l1_size_log2 = std::max(l1_size_log2, kernel_width_log2);
  l1_size_log2 = std::min(l1_size_log2, size_floor_log2);
  - l1_size_log2 = std::max(l1_size_log2, size_floor_log2 - 8);
  int num_blocks_base_log2 = size_floor_log2 - l1_size_log2;
  RUY_DCHECK_GE(num_blocks_base_log2, 0);
  - RUY_DCHECK_LE(num_blocks_base_log2, 8);
  if (num_blocks_base_log2 == 0) {
  if ((rows % kernel_rows) || (cols % kernel_cols)) {
  num_blocks_base_log2 = 1;
  }
  }
  - RUY_DCHECK_LE(num_blocks_base_log2 + rows_rectangularness_log2, 16);
  - RUY_DCHECK_LE(num_blocks_base_log2 + cols_rectangularness_log2, 16);
  int rows_rounded_up = round_up_pot(rows, kernel_rows);
  int cols_rounded_up = round_up_pot(cols, kernel_cols);
  