msm: vidc: refinements for lossless encoding

1. Refine work mode to 2 and disable low latency by default;
2. Refine output buffer size to (width * height) * 9 / 4;
3. Double scratch buffer size for lossless encoding;

Change-Id: If298b9fc63fc2329f02dcfcef5e4fd0667d3e8e6
Signed-off-by: Shi Zhongbo <zhongbos@codeaurora.org>