fix cupyx -> cupy
fix cupyx -> cupy

hvy/chainer,chainer/chainer,okuta/chainer,wkentaro/chainer,okuta/chainer,pfnet/chainer,hvy/chainer,chainer/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,niboshi/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,chainer/chainer,hvy/chainer,wkentaro/chainer,wkentaro/chainer,niboshi/chainer,okuta/chainer