A problem about the unsupervised mask of mixed images.

[randydkx]

@ShikunLi Hi, I find an error in the compute of unsupervised mask of mixed image, here we should let mask2Unsup_batch be the same mask matrix as maskUnsup_batch and mask2Unsup_mem be the same as maskUnsup_mem. Because we passpairwise_comp_batch to function Supervised_ContrastiveLearning_loss and elements in pairwise_comp_batch is positive diagnally.