This commit added coments for the following encoder controls:
VP9E_SET_LOSSLESS
VP9E_SET_TILE_COLUMNS
VP9E_SET_TILE_ROWS
VP9E_SET_FRAME_PARALLEL_DECODING
VP9E_SET_AQ_MODE

Change-Id: I2f75afd9cce01394f202b8e25f36bf763be0ddeb