StageFrightRecorder: do not use meta-data mode for software encoders

Camera HAL v1 uses vendor-specific camera-source meta-data mode, but
software encoders use generic gralloc-source mode, so they are not
compatible.

Change-Id: I0d1bab8eada26dcb70c97b1eec83f06d1f331239
Signed-off-by: Lajos Molnar <lajos@google.com>
Bug: 11446505