Fix coverity warning.
Fix coverity warning.

- A false alarm about buffer overflow. No new modes are added if all modes
  are already in the list.
- Skip checking predicted modes if all modes are in the list.

ultravideo/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar