According to the VVC specification (section 8.5.1), the maximum width/height of a subblock passed for DMVR SAD is 16. This along with previous constraint requiring width * height >= 128 means that 8x16, 16x8, and 16x16 are the only allowed sizes. This re-labels vvc_sad_16_128 to vvc_sad_16 to reflect this and adds a comment about the block size constraints. There's no functionality change.