bug fix in JVET_L0694_AFFINE_LINEBUFFER_CLEANUP
In function xCheckIdenticalMotion, motion vectors in top-left, top-right, bottom-left sub-blocks were used to check identical motion in list 0 and list 1. But after JVET_L0694_AFFINE_LINEBUFFER_CLEANUP was adopted, a separate buffer
mvAffi was used for storing affine motion seed. Same motion vector top-left, top-right, bottom-left sub-blocks did not mean same motion field for the whole PU as before.
mvAffi can represent the motion field for the whole PU so should be used for comparison.