[NORMATIVE] Fix clamping in get_mv_projection()
[NORMATIVE] Fix clamping in get_mv_projection()

get_mv_projection() is currently able to produce motion vectors which
are invalid (according to is_mv_valid() in the decoder). This can be
fixed by adjusting the range of the clamp operation.

BUG=aomedia:1947

Change-Id: I309463be4be868a20042ac26307b84efb63665d6

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom