[flang] Fix character length calculation for Unicode component

[klausler]

Summary

The character length value in the derived type component information table
entry is already in units of characters, not bytes, so don't divide by the
per-character byte size.

flang/runtime/type-info.cpp

   if (cat == TypeCategory::Character) {
     std::size_t lengthInChars{0};
     if (auto length{characterLen_.GetValue(&container)}) {
-      lengthInChars = static_cast<std::size_t>(*length / kind_);
+      lengthInChars = static_cast<std::size_t>(*length);
     } else {
       RUNTIME_CHECK(
           terminator, characterLen_.genre() == Value::Genre::Deferred);